Step-by-step Maths Level 3: Adding 3-digit numbers with carrying

Method. Add the ones, then the tens, then the hundreds. Carry any ten or hundred you make.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   707 over 128
2. 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
3. Add the tens. Add the carried ten with the tens.
   0 + 2 + 1 carried = 3
4. Add the hundreds. Add any carried hundred too.
   7 + 1 = 8
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   780 over 76
2. Add the ones. The ones make less than 10, so no ten is carried.
   0 + 6 = 6
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 + 7 = 15
4. Add the hundreds. Add any carried hundred too.
   7 + 0 + 1 carried = 8
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   338 over 94
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   3 + 0 + 1 carried = 4
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   781 over 62
2. Add the ones. The ones make less than 10, so no ten is carried.
   1 + 2 = 3
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
4. Add the hundreds. Add any carried hundred too.
   7 + 0 + 1 carried = 8
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   304 over 39
2. 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
3. Add the tens. Add the carried ten with the tens.
   0 + 3 + 1 carried = 4
4. Add the hundreds. Add any carried hundred too.
   3 + 0 = 3
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   365 over 386
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   3 + 3 + 1 carried = 7
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   607 over 99
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   6 + 0 + 1 carried = 7
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   247 over 564
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   2 + 5 + 1 carried = 8
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   773 over 192
2. Add the ones. The ones make less than 10, so no ten is carried.
   3 + 2 = 5
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 + 9 = 16
4. Add the hundreds. Add any carried hundred too.
   7 + 1 + 1 carried = 9
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   217 over 74
2. 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
3. Add the tens. Add the carried ten with the tens.
   1 + 7 + 1 carried = 9
4. Add the hundreds. Add any carried hundred too.
   2 + 0 = 2
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   842 over 78
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   8 + 0 + 1 carried = 9
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   206 over 56
2. 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
3. Add the tens. Add the carried ten with the tens.
   0 + 5 + 1 carried = 6
4. Add the hundreds. Add any carried hundred too.
   2 + 0 = 2
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   638 over 189
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   6 + 1 + 1 carried = 8
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   627 over 97
2. 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
3. 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
4. Add the hundreds. Add any carried hundred too.
   6 + 0 + 1 carried = 7
5. 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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   537 over 38
2. 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
3. Add the tens. Add the carried ten with the tens.
   3 + 3 + 1 carried = 7
4. Add the hundreds. Add any carried hundred too.
   5 + 0 = 5
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.

1. Write the numbers in columns. Keep the ones under the ones and the tens under the tens.
   794 over 14
2. Add the ones. The ones make less than 10, so no ten is carried.
   4 + 4 = 8
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.
   9 + 1 = 10
4. Add the hundreds. Add any carried hundred too.
   7 + 0 + 1 carried = 8
5. 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.