Adding within 1000
By the end of this chapter you will be able to
- Add a 1-digit number with carrying
- Add two 2-digit numbers with carrying
- Add 3-digit numbers with carrying
- Estimate and check answers
- Solve addition word problems
You should already know
- Adding within 100 without carrying (Level 2, chapter 7)
- Hundreds, tens and ones (chapter 2)
Where this leads
- Subtracting within 1000 (chapter 5)
Step-by-step practice: maths (Level 3). Small steps, repeated until fluent. Content: Add a 1-digit number to a 2-digit or 3-digit number, with carrying from the ones to the tens, Add two 2-digit numbers with carrying from the ones or the tens, Add 3-digit numbers with carrying from the tens to the hundreds, Set sums out in columns with hundreds, tens and ones lined up, Add in any order, estimate the answer first and check it is close, and solve one-step word problems.
Exercise P Do you remember?
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.23 over 45
- Add the ones. The ones make less than 10, so no ten is carried.3 + 5 = 8
- Add the tens. There is no carried ten to add.2 + 4 = 6
- Write the answer. Read the columns from left to right.68
Check. Check: 68 - 45 = 23.
Watch out. Add the ones first. Carry every ten you make into the next column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.31 over 27
- Add the ones. The ones make less than 10, so no ten is carried.1 + 7 = 8
- Add the tens. There is no carried ten to add.3 + 2 = 5
- Write the answer. Read the columns from left to right.58
Check. Check: 58 - 27 = 31.
Watch out. Add the ones first. Carry every ten you make into the next column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.42 over 36
- Add the ones. The ones make less than 10, so no ten is carried.2 + 6 = 8
- Add the tens. There is no carried ten to add.4 + 3 = 7
- Write the answer. Read the columns from left to right.78
Check. Check: 78 - 36 = 42.
Watch out. Add the ones first. Carry every ten you make into the next column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.52 over 36
- Add the ones. The ones make less than 10, so no ten is carried.2 + 6 = 8
- Add the tens. There is no carried ten to add.5 + 3 = 8
- Write the answer. Read the columns from left to right.88
Check. Check: 88 - 36 = 52.
Watch out. Add the ones first. Carry every ten you make into the next column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.61 over 18
- Add the ones. The ones make less than 10, so no ten is carried.1 + 8 = 9
- Add the tens. There is no carried ten to add.6 + 1 = 7
- Write the answer. Read the columns from left to right.79
Check. Check: 79 - 18 = 61.
Watch out. Add the ones first. Carry every ten you make into the next column.
Adding a 1-digit number with carrying
Sometimes the ones add to 10 or more. Then we carry one ten into the tens column.
Add the ones first. Write the ones digit of the answer, and carry the ten to the tens.
Key ideas
- Add the ones first.
- If the ones make 10 or more, carry 1 ten.
- Add the carried ten to the tens.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.38 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 7 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.3 + 0 + 1 carried = 4
- Write the answer. Read the columns from left to right.45
Check. Check: 45 - 7 = 38.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.267 over 8
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 8 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.6 + 0 + 1 carried = 7
- Add the hundreds. Add any carried hundred too.2 + 0 = 2
- Write the answer. Read the columns from left to right.275
Check. Check: 275 - 8 = 267.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.59 over 6
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.9 + 6 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.5 + 0 + 1 carried = 6
- Write the answer. Read the columns from left to right.65
Check. Check: 65 - 6 = 59.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Watch out
Watch out. Do not forget the carried ten. 38 + 7 is 45, not 35.
Exam tip
Grown-up tip. Use ten sticks and ones cubes. Make ten ones into a stick and put it with the tens.
Exercise 4A Practice: a 1-digit number with carrying
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.52 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.2 + 9 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.5 + 0 + 1 carried = 6
- Write the answer. Read the columns from left to right.61
Check. Check: 61 - 9 = 52.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.415 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 7 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 0 + 1 carried = 2
- Add the hundreds. Add any carried hundred too.4 + 0 = 4
- Write the answer. Read the columns from left to right.422
Check. Check: 422 - 7 = 415.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.656 over 4
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 4 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.5 + 0 + 1 carried = 6
- Add the hundreds. Add any carried hundred too.6 + 0 = 6
- Write the answer. Read the columns from left to right.660
Check. Check: 660 - 4 = 656.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.95 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 9 = 14, write 4 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 0 + 1 carried = 10
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.104
Check. Check: 104 - 9 = 95.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.477 over 3
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 3 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.7 + 0 + 1 carried = 8
- Add the hundreds. Add any carried hundred too.4 + 0 = 4
- Write the answer. Read the columns from left to right.480
Check. Check: 480 - 3 = 477.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.503 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 7 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.0 + 0 + 1 carried = 1
- Add the hundreds. Add any carried hundred too.5 + 0 = 5
- Write the answer. Read the columns from left to right.510
Check. Check: 510 - 7 = 503.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.978 over 5
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 5 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens.7 + 0 + 1 carried = 8
- Add the hundreds. Add any carried hundred too.9 + 0 = 9
- Write the answer. Read the columns from left to right.983
Check. Check: 983 - 5 = 978.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.836 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 7 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens.3 + 0 + 1 carried = 4
- Add the hundreds. Add any carried hundred too.8 + 0 = 8
- Write the answer. Read the columns from left to right.843
Check. Check: 843 - 7 = 836.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.86 over 8
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 8 = 14, write 4 and carry 1
- Add the tens. Add the carried ten with the tens.8 + 0 + 1 carried = 9
- Write the answer. Read the columns from left to right.94
Check. Check: 94 - 8 = 86.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.18 over 3
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 3 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 0 + 1 carried = 2
- Write the answer. Read the columns from left to right.21
Check. Check: 21 - 3 = 18.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.725 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 7 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.2 + 0 + 1 carried = 3
- Add the hundreds. Add any carried hundred too.7 + 0 = 7
- Write the answer. Read the columns from left to right.732
Check. Check: 732 - 7 = 725.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.372 over 8
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.2 + 8 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.7 + 0 + 1 carried = 8
- Add the hundreds. Add any carried hundred too.3 + 0 = 3
- Write the answer. Read the columns from left to right.380
Check. Check: 380 - 8 = 372.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.844 over 8
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.4 + 8 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.4 + 0 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.8 + 0 = 8
- Write the answer. Read the columns from left to right.852
Check. Check: 852 - 8 = 844.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.528 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 9 = 17, write 7 and carry 1
- Add the tens. Add the carried ten with the tens.2 + 0 + 1 carried = 3
- Add the hundreds. Add any carried hundred too.5 + 0 = 5
- Write the answer. Read the columns from left to right.537
Check. Check: 537 - 9 = 528.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.453 over 7
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 7 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.5 + 0 + 1 carried = 6
- Add the hundreds. Add any carried hundred too.4 + 0 = 4
- Write the answer. Read the columns from left to right.460
Check. Check: 460 - 7 = 453.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.279 over 2
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.9 + 2 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.7 + 0 + 1 carried = 8
- Add the hundreds. Add any carried hundred too.2 + 0 = 2
- Write the answer. Read the columns from left to right.281
Check. Check: 281 - 2 = 279.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Adding two 2-digit numbers with carrying
Two 2-digit numbers can need carrying. The ones may make 10 or more, and the tens may then make 10 or more as well.
When the tens make 10 or more, the answer goes into the hundreds. That is a sum of 100 or more.
Key ideas
- Add the ones, then the tens.
- Carry a ten when the ones make 10 or more.
- Carry a hundred when the tens make 10 or more.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.47 over 38
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 8 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.4 + 3 + 1 carried = 8
- Write the answer. Read the columns from left to right.85
Check. Check: 85 - 38 = 47.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.65 over 58
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 8 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 5 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.123
Check. Check: 123 - 58 = 65.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.76 over 49
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 9 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 4 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.125
Check. Check: 125 - 49 = 76.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Watch out
Watch out. Add the carried ten to the tens before you write them down. 76 + 49 is 125, not 115.
Exam tip
Grown-up tip. Ask: “How many ones? Is it ten or more? How many tens, with the one we carried?”
Exercise 4B Practice: two 2-digit numbers with carrying
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.72 over 30
- Add the ones. The ones make less than 10, so no ten is carried.2 + 0 = 2
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 3 = 10
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.102
Check. Check: 102 - 30 = 72.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.92 over 57
- Add the ones. The ones make less than 10, so no ten is carried.2 + 7 = 9
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 5 = 14
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.149
Check. Check: 149 - 57 = 92.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.44 over 70
- Add the ones. The ones make less than 10, so no ten is carried.4 + 0 = 4
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 7 = 11
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.114
Check. Check: 114 - 70 = 44.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.79 over 43
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.9 + 3 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 4 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.122
Check. Check: 122 - 43 = 79.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.82 over 90
- Add the ones. The ones make less than 10, so no ten is carried.2 + 0 = 2
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 9 = 17
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.172
Check. Check: 172 - 90 = 82.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.73 over 70
- Add the ones. The ones make less than 10, so no ten is carried.3 + 0 = 3
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 7 = 14
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.143
Check. Check: 143 - 70 = 73.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.97 over 65
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 5 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 6 + 1 carried = 16
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.162
Check. Check: 162 - 65 = 97.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.83 over 87
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 7 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 8 + 1 carried = 17
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.170
Check. Check: 170 - 87 = 83.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.60 over 77
- Add the ones. The ones make less than 10, so no ten is carried.0 + 7 = 7
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 7 = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.137
Check. Check: 137 - 77 = 60.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.48 over 14
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 4 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.4 + 1 + 1 carried = 6
- Write the answer. Read the columns from left to right.62
Check. Check: 62 - 14 = 48.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.89 over 83
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.9 + 3 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 8 + 1 carried = 17
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.172
Check. Check: 172 - 83 = 89.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.44 over 91
- Add the ones. The ones make less than 10, so no ten is carried.4 + 1 = 5
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 9 = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.135
Check. Check: 135 - 91 = 44.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.88 over 48
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 8 = 16, write 6 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 4 + 1 carried = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.136
Check. Check: 136 - 48 = 88.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.80 over 94
- Add the ones. The ones make less than 10, so no ten is carried.0 + 4 = 4
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 9 = 17
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.174
Check. Check: 174 - 94 = 80.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.57 over 75
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 5 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.5 + 7 + 1 carried = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.132
Check. Check: 132 - 75 = 57.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.87 over 51
- Add the ones. The ones make less than 10, so no ten is carried.7 + 1 = 8
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 5 = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.138
Check. Check: 138 - 51 = 87.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Adding 3-digit numbers with carrying
Line up the hundreds, tens and ones in columns. Then add the ones, the tens and the hundreds in that order.
Carry a ten from one column to the next, and carry a hundred from the tens to the hundreds when needed.
Key ideas
- Line up the columns.
- Add the ones, then the tens, then the hundreds.
- Carry from each column to the next.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.386 over 275
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 5 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 7 + 1 carried = 16
- Add the hundreds. Add any carried hundred too.3 + 2 + 1 carried = 6
- Write the answer. Read the columns from left to right.661
Check. Check: 661 - 275 = 386.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.452 over 89
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.2 + 9 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.5 + 8 + 1 carried = 14
- Add the hundreds. Add any carried hundred too.4 + 0 + 1 carried = 5
- Write the answer. Read the columns from left to right.541
Check. Check: 541 - 89 = 452.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.608 over 97
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 7 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.0 + 9 + 1 carried = 10
- Add the hundreds. Add any carried hundred too.6 + 0 + 1 carried = 7
- Write the answer. Read the columns from left to right.705
Check. Check: 705 - 97 = 608.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Watch out
Watch out. Keep the digits in their columns. 608 + 97 has a 9 in the tens, not the hundreds, so it is 705.
Exam tip
Grown-up tip. Draw the columns on squared paper, with one digit in each square. Ask the child to say the carried number out loud.
Exercise 4C Practice: 3-digit numbers with carrying
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.707 over 128
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 8 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.0 + 2 + 1 carried = 3
- Add the hundreds. Add any carried hundred too.7 + 1 = 8
- Write the answer. Read the columns from left to right.835
Check. Check: 835 - 128 = 707.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.780 over 76
- Add the ones. The ones make less than 10, so no ten is carried.0 + 6 = 6
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 7 = 15
- Add the hundreds. Add any carried hundred too.7 + 0 + 1 carried = 8
- Write the answer. Read the columns from left to right.856
Check. Check: 856 - 76 = 780.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.338 over 94
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 4 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.3 + 9 + 1 carried = 13
- Add the hundreds. Add any carried hundred too.3 + 0 + 1 carried = 4
- Write the answer. Read the columns from left to right.432
Check. Check: 432 - 94 = 338.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.781 over 62
- Add the ones. The ones make less than 10, so no ten is carried.1 + 2 = 3
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 6 = 14
- Add the hundreds. Add any carried hundred too.7 + 0 + 1 carried = 8
- Write the answer. Read the columns from left to right.843
Check. Check: 843 - 62 = 781.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.304 over 39
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.4 + 9 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens.0 + 3 + 1 carried = 4
- Add the hundreds. Add any carried hundred too.3 + 0 = 3
- Write the answer. Read the columns from left to right.343
Check. Check: 343 - 39 = 304.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.365 over 386
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 6 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 8 + 1 carried = 15
- Add the hundreds. Add any carried hundred too.3 + 3 + 1 carried = 7
- Write the answer. Read the columns from left to right.751
Check. Check: 751 - 386 = 365.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.607 over 99
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 9 = 16, write 6 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.0 + 9 + 1 carried = 10
- Add the hundreds. Add any carried hundred too.6 + 0 + 1 carried = 7
- Write the answer. Read the columns from left to right.706
Check. Check: 706 - 99 = 607.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.247 over 564
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 4 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 6 + 1 carried = 11
- Add the hundreds. Add any carried hundred too.2 + 5 + 1 carried = 8
- Write the answer. Read the columns from left to right.811
Check. Check: 811 - 564 = 247.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.773 over 192
- Add the ones. The ones make less than 10, so no ten is carried.3 + 2 = 5
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 9 = 16
- Add the hundreds. Add any carried hundred too.7 + 1 + 1 carried = 9
- Write the answer. Read the columns from left to right.965
Check. Check: 965 - 192 = 773.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.217 over 74
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 4 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 7 + 1 carried = 9
- Add the hundreds. Add any carried hundred too.2 + 0 = 2
- Write the answer. Read the columns from left to right.291
Check. Check: 291 - 74 = 217.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.842 over 78
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.2 + 8 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 7 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.8 + 0 + 1 carried = 9
- Write the answer. Read the columns from left to right.920
Check. Check: 920 - 78 = 842.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.206 over 56
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 6 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.0 + 5 + 1 carried = 6
- Add the hundreds. Add any carried hundred too.2 + 0 = 2
- Write the answer. Read the columns from left to right.262
Check. Check: 262 - 56 = 206.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.638 over 189
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 9 = 17, write 7 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.3 + 8 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.6 + 1 + 1 carried = 8
- Write the answer. Read the columns from left to right.827
Check. Check: 827 - 189 = 638.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.627 over 97
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 7 = 14, write 4 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.2 + 9 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.6 + 0 + 1 carried = 7
- Write the answer. Read the columns from left to right.724
Check. Check: 724 - 97 = 627.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.537 over 38
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 8 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.3 + 3 + 1 carried = 7
- Add the hundreds. Add any carried hundred too.5 + 0 = 5
- Write the answer. Read the columns from left to right.575
Check. Check: 575 - 38 = 537.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.794 over 14
- Add the ones. The ones make less than 10, so no ten is carried.4 + 4 = 8
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 1 = 10
- Add the hundreds. Add any carried hundred too.7 + 0 + 1 carried = 8
- Write the answer. Read the columns from left to right.808
Check. Check: 808 - 14 = 794.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Word problems, adding in any order, and estimating
Read the problem and find the word that tells you to add. Words like altogether, more and in all mean add.
An estimate tells you roughly what the answer should be. Round the numbers, add them, then check the exact answer is close.
Key ideas
- Words like altogether and more mean add.
- Adding in any order gives the same total.
- An estimate should be close to the exact answer.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.178 + 56
- Work out the total. Use column addition with the ones first.178 + 56 = 234
- Write the answer. This is the total in the question.234
Check. Check: 234 - 56 = 178.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.246 + 97
- Work out the total. Use column addition with the ones first.246 + 97 = 343
- Write the answer. This is the total in the question.343
Check. Check: 343 - 97 = 246.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.312 + 79
- Work out the total. Use column addition with the ones first.312 + 79 = 391
- Write the answer. This is the total in the question.391
Check. Check: 391 - 79 = 312.
Watch out. Look for words like more, altogether and in all. These mean add.
Watch out
Watch out. Check that your answer is close to the estimate. If it is not, check the carrying.
Exam tip
Grown-up tip. Ask: “Is the answer about the right size? Did you carry the ten?”
Exercise 4D Practice: word problems and estimates
Non-calculatorMethod. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.457 + 194
- Work out the total. Use column addition with the ones first.457 + 194 = 651
- Write the answer. This is the total in the question.651
Check. Check: 651 - 194 = 457.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.32 + 171
- Work out the total. Use column addition with the ones first.32 + 171 = 203
- Write the answer. This is the total in the question.203
Check. Check: 203 - 171 = 32.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.427 + 16
- Work out the total. Use column addition with the ones first.427 + 16 = 443
- Write the answer. This is the total in the question.443
Check. Check: 443 - 16 = 427.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.592 + 358
- Work out the total. Use column addition with the ones first.592 + 358 = 950
- Write the answer. This is the total in the question.950
Check. Check: 950 - 358 = 592.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.336 + 177
- Work out the total. Use column addition with the ones first.336 + 177 = 513
- Write the answer. This is the total in the question.513
Check. Check: 513 - 177 = 336.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.215 + 49
- Work out the total. Use column addition with the ones first.215 + 49 = 264
- Write the answer. This is the total in the question.264
Check. Check: 264 - 49 = 215.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.348 + 98
- Work out the total. Use column addition with the ones first.348 + 98 = 446
- Write the answer. This is the total in the question.446
Check. Check: 446 - 98 = 348.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.555 + 356
- Work out the total. Use column addition with the ones first.555 + 356 = 911
- Write the answer. This is the total in the question.911
Check. Check: 911 - 356 = 555.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.495 over 448
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 8 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 4 + 1 carried = 14
- Add the hundreds. Add any carried hundred too.4 + 4 + 1 carried = 9
- Write the answer. Read the columns from left to right.943
Check. Check: 943 - 448 = 495.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.448 over 495
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.8 + 5 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 9 + 1 carried = 14
- Add the hundreds. Add any carried hundred too.4 + 4 + 1 carried = 9
- Write the answer. Read the columns from left to right.943
Check. Check: 943 - 495 = 448.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.599 over 323
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.9 + 3 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.9 + 2 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.5 + 3 + 1 carried = 9
- Write the answer. Read the columns from left to right.922
Check. Check: 922 - 323 = 599.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.323 over 599
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 9 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.2 + 9 + 1 carried = 12
- Add the hundreds. Add any carried hundred too.3 + 5 + 1 carried = 9
- Write the answer. Read the columns from left to right.922
Check. Check: 922 - 599 = 323.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.327 over 124
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 4 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.2 + 2 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.3 + 1 = 4
- Write the answer. Read the columns from left to right.451
Check. Check: 451 - 124 = 327.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.124 over 327
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.4 + 7 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.2 + 2 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.1 + 3 = 4
- Write the answer. Read the columns from left to right.451
Check. Check: 451 - 327 = 124.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.860 over 59
- Add the ones. The ones make less than 10, so no ten is carried.0 + 9 = 9
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 5 = 11
- Add the hundreds. Add any carried hundred too.8 + 0 + 1 carried = 9
- Write the answer. Read the columns from left to right.919
Check. Check: 919 - 59 = 860.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.59 over 860
- Add the ones. The ones make less than 10, so no ten is carried.9 + 0 = 9
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.5 + 6 = 11
- Add the hundreds. Add any carried hundred too.0 + 8 + 1 carried = 9
- Write the answer. Read the columns from left to right.919
Check. Check: 919 - 860 = 59.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Round each number to the nearest hundred, then add the rounded numbers.
- Round 716 to the nearest hundred. Look at the tens and ones.716 is about 700
- Round 137 to the nearest hundred. Look at the tens and ones.137 is about 100
- Add the rounded numbers. This is the estimate.800
Check. The exact answer 853 should be close to 800.
Watch out. An estimate tells us roughly where the answer should be. It does not have to be exact.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.716 over 137
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 7 = 13, write 3 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 3 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.7 + 1 = 8
- Write the answer. Read the columns from left to right.853
Check. Check: 853 - 137 = 716.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Round each number to the nearest hundred, then add the rounded numbers.
- Round 717 to the nearest hundred. Look at the tens and ones.717 is about 700
- Round 83 to the nearest hundred. Look at the tens and ones.83 is about 100
- Add the rounded numbers. This is the estimate.800
Check. The exact answer 800 should be close to 800.
Watch out. An estimate tells us roughly where the answer should be. It does not have to be exact.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.717 over 83
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 3 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.1 + 8 + 1 carried = 10
- Add the hundreds. Add any carried hundred too.7 + 0 + 1 carried = 8
- Write the answer. Read the columns from left to right.800
Check. Check: 800 - 83 = 717.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Round each number to the nearest hundred, then add the rounded numbers.
- Round 213 to the nearest hundred. Look at the tens and ones.213 is about 200
- Round 639 to the nearest hundred. Look at the tens and ones.639 is about 600
- Add the rounded numbers. This is the estimate.800
Check. The exact answer 852 should be close to 800.
Watch out. An estimate tells us roughly where the answer should be. It does not have to be exact.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.213 over 639
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 9 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 3 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.2 + 6 = 8
- Write the answer. Read the columns from left to right.852
Check. Check: 852 - 639 = 213.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Round each number to the nearest hundred, then add the rounded numbers.
- Round 742 to the nearest hundred. Look at the tens and ones.742 is about 700
- Round 118 to the nearest hundred. Look at the tens and ones.118 is about 100
- Add the rounded numbers. This is the estimate.800
Check. The exact answer 860 should be close to 800.
Watch out. An estimate tells us roughly where the answer should be. It does not have to be exact.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.742 over 118
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.2 + 8 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.4 + 1 + 1 carried = 6
- Add the hundreds. Add any carried hundred too.7 + 1 = 8
- Write the answer. Read the columns from left to right.860
Check. Check: 860 - 118 = 742.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Chapter summary
| Skill | Method |
|---|---|
| Add a 1-digit number | Add the ones; if they make 10 or more, carry a ten |
| Add two 2-digit numbers | Add the ones, then the tens; carry when needed |
| Add 3-digit numbers | Line up the columns; add ones, tens, hundreds; carry as you go |
| Check an answer | Estimate first by rounding; check the answer is close |
Can you…?
- I can add a 1-digit number to a 2-digit or 3-digit number, with carrying
- I can add two 2-digit numbers, carrying from the ones or the tens
- I can add two 3-digit numbers, carrying from the tens to the hundreds
- I can set out a sum in columns, with the digits lined up
- I can estimate an answer and check my answer is close
Key terms
- carry
- move a ten to the next column when a column makes 10 or more
- column method
- writing numbers in columns so the digits line up
- estimate
- a sensible guess that is close to the exact answer
- altogether
- a word that often means add
Exercise 4Z Check-up
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.43 over 85
- Add the ones. The ones make less than 10, so no ten is carried.3 + 5 = 8
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 8 = 12
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.128
Check. Check: 128 - 85 = 43.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.372 + 109
- Work out the total. Use column addition with the ones first.372 + 109 = 481
- Write the answer. This is the total in the question.481
Check. Check: 481 - 109 = 372.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.521 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.1 + 9 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.2 + 0 + 1 carried = 3
- Add the hundreds. Add any carried hundred too.5 + 0 = 5
- Write the answer. Read the columns from left to right.530
Check. Check: 530 - 9 = 521.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.126 + 257
- Work out the total. Use column addition with the ones first.126 + 257 = 383
- Write the answer. This is the total in the question.383
Check. Check: 383 - 257 = 126.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.916 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 9 = 15, write 5 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 0 + 1 carried = 2
- Add the hundreds. Add any carried hundred too.9 + 0 = 9
- Write the answer. Read the columns from left to right.925
Check. Check: 925 - 9 = 916.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.356 over 80
- Add the ones. The ones make less than 10, so no ten is carried.6 + 0 = 6
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.5 + 8 = 13
- Add the hundreds. Add any carried hundred too.3 + 0 + 1 carried = 4
- Write the answer. Read the columns from left to right.436
Check. Check: 436 - 80 = 356.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.74 + 193
- Work out the total. Use column addition with the ones first.74 + 193 = 267
- Write the answer. This is the total in the question.267
Check. Check: 267 - 193 = 74.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.437 over 309
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 9 = 16, write 6 and carry 1
- Add the tens. Add the carried ten with the tens.3 + 0 + 1 carried = 4
- Add the hundreds. Add any carried hundred too.4 + 3 = 7
- Write the answer. Read the columns from left to right.746
Check. Check: 746 - 309 = 437.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.686 over 96
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 6 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.8 + 9 + 1 carried = 18
- Add the hundreds. Add any carried hundred too.6 + 0 + 1 carried = 7
- Write the answer. Read the columns from left to right.782
Check. Check: 782 - 96 = 686.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.31 over 99
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.1 + 9 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.3 + 9 + 1 carried = 13
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.130
Check. Check: 130 - 99 = 31.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Total 19 marks. Allow about 19 minutes.
Exercise 4X Practice test questions
Non-calculatorMethod. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.68 over 50
- Add the ones. The ones make less than 10, so no ten is carried.8 + 0 = 8
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 5 = 11
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.118
Check. Check: 118 - 50 = 68.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.77 over 85
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.7 + 5 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.7 + 8 + 1 carried = 16
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.162
Check. Check: 162 - 85 = 77.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.636 over 35
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.6 + 5 = 11, write 1 and carry 1
- Add the tens. Add the carried ten with the tens.3 + 3 + 1 carried = 7
- Add the hundreds. Add any carried hundred too.6 + 0 = 6
- Write the answer. Read the columns from left to right.671
Check. Check: 671 - 35 = 636.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.141 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.1 + 9 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens.4 + 0 + 1 carried = 5
- Add the hundreds. Add any carried hundred too.1 + 0 = 1
- Write the answer. Read the columns from left to right.150
Check. Check: 150 - 9 = 141.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.307 + 339
- Work out the total. Use column addition with the ones first.307 + 339 = 646
- Write the answer. This is the total in the question.646
Check. Check: 646 - 339 = 307.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.566 over 61
- Add the ones. The ones make less than 10, so no ten is carried.6 + 1 = 7
- Add the tens. There is no carried ten to add. The tens make 10 or more, so write the tens digit and carry 1 hundred.6 + 6 = 12
- Add the hundreds. Add any carried hundred too.5 + 0 + 1 carried = 6
- Write the answer. Read the columns from left to right.627
Check. Check: 627 - 61 = 566.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.613 over 9
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.3 + 9 = 12, write 2 and carry 1
- Add the tens. Add the carried ten with the tens.1 + 0 + 1 carried = 2
- Add the hundreds. Add any carried hundred too.6 + 0 = 6
- Write the answer. Read the columns from left to right.622
Check. Check: 622 - 9 = 613.
Watch out. When the ones make 10 or more, carry a ten to the tens column. Do not forget it.
Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.
- Write the numbers in columns. Keep the ones under the ones and the tens under the tens.45 over 95
- Add the ones. The ones make 10 or more, so write the ones digit and carry 1 ten.5 + 5 = 10, write 0 and carry 1
- Add the tens. Add the carried ten with the tens. The tens make 10 or more, so write the tens digit and carry 1 hundred.4 + 9 + 1 carried = 14
- Add the hundreds. Add any carried hundred too.0 + 0 + 1 carried = 1
- Write the answer. Read the columns from left to right.140
Check. Check: 140 - 95 = 45.
Watch out. When the tens make 10 or more, carry a hundred to the hundreds column.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.287 + 205
- Work out the total. Use column addition with the ones first.287 + 205 = 492
- Write the answer. This is the total in the question.492
Check. Check: 492 - 205 = 287.
Watch out. Look for words like more, altogether and in all. These mean add.
Method. Find the operation, then work out the total.
- Find the operation. We are putting two amounts together, so we add.435 + 289
- Work out the total. Use column addition with the ones first.435 + 289 = 724
- Write the answer. This is the total in the question.724
Check. Check: 724 - 289 = 435.
Watch out. Look for words like more, altogether and in all. These mean add.