Step-by-step Maths Level 4 Column addition and subtraction: check-up and practice test questions

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   5 + 2 = 7: Write 7. There is nothing to carry.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   4 + 3 = 7: Write 7. There is nothing to carry.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   3 + 8 = 11: Write 1 and carry 1 to the next column.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   4 + 1 + 1 = 6: Write 6. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   6177

Check. Check: 6177 - 1832 = 4345.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Use the inverse operation to find the missing number.

1. Find what must be added. The missing number is the difference between the total and the known number.
   9149 - 6084 = 3065
2. Write the missing number. Check it fills the gap.
   3065

Check. Check: 6084 + 3065 = 9149.

Watch out. Addition and subtraction undo each other. Use the operation that undoes the one in the question.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Subtract the ones column. Take the bottom digit from the top digit.
   5 - 0 = 5
2. Exchange in the hundreds column. The tens digit is too small, so exchange 1 hundred for 10 tens.
   hundreds: 9 to 8; tens: 3 to 13
3. Subtract the tens column. Take the bottom digit from the top digit.
   13 - 6 = 7
4. Subtract the hundreds column. Take the bottom digit from the top digit.
   8 - 8 = 0
5. Subtract the thousands column. Take the bottom digit from the top digit.
   9 - 5 = 4
6. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   4075

Check. Check: 4075 + 5860 = 9935.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Method. Use the inverse operation to find the missing number.

1. Find what must be added. The missing number is the difference between the total and the known number.
   8598 - 7526 = 1072
2. Write the missing number. Check it fills the gap.
   1072

Check. Check: 7526 + 1072 = 8598.

Watch out. Addition and subtraction undo each other. Use the operation that undoes the one in the question.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Subtract the ones column. Take the bottom digit from the top digit.
   5 - 2 = 3
2. Exchange in the thousands column. The hundreds are 0, so exchange from further left: exchange 1 thousand for 10 hundreds.
   thousands: 4 to 3; hundreds: 0 to 10
3. Exchange in the hundreds column. The tens digit is too small, so exchange 1 hundred for 10 tens.
   hundreds: 10 to 9; tens: 1 to 11
4. Subtract the tens column. Take the bottom digit from the top digit.
   11 - 9 = 2
5. Subtract the hundreds column. Take the bottom digit from the top digit.
   9 - 1 = 8
6. Subtract the thousands column. Take the bottom digit from the top digit.
   3 - 1 = 2
7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   2823

Check. Check: 2823 + 1192 = 4015.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   9 + 3 = 12: Write 2 and carry 1 to the next column.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   8 + 5 + 1 = 14: Write 4 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   8 + 6 + 1 = 15: Write 5 and carry 1 to the next column.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   6 + 2 + 1 = 9: Write 9. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   9542

Check. Check: 9542 - 2653 = 6889.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   7 + 6 = 13: Write 3 and carry 1 to the next column.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   7 + 2 + 1 = 10: Write 0 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   2 + 6 + 1 = 9: Write 9. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   8 + 1 = 9: Write 9. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   9903

Check. Check: 9903 - 1626 = 8277.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Subtract the ones column. Take the bottom digit from the top digit.
   9 - 9 = 0
2. Exchange in the hundreds column. The tens digit is too small, so exchange 1 hundred for 10 tens.
   hundreds: 3 to 2; tens: 1 to 11
3. Subtract the tens column. Take the bottom digit from the top digit.
   11 - 8 = 3
4. Exchange in the thousands column. The hundreds digit is too small, so exchange 1 thousand for 10 hundreds.
   thousands: 7 to 6; hundreds: 2 to 12
5. Subtract the hundreds column. Take the bottom digit from the top digit.
   12 - 4 = 8
6. Subtract the thousands column. Take the bottom digit from the top digit.
   6 - 4 = 2
7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   2830

Check. Check: 2830 + 4489 = 7319.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   3 + 2 = 5: Write 5. There is nothing to carry.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   7 + 4 = 11: Write 1 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   0 + 3 + 1 = 4: Write 4. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   1 + 3 = 4: Write 4. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   4415

Check. Check: 4415 - 3342 = 1073.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Change only the column that matches the number you add or take away.

1. Find the hundred digit in 9780. Only the hundred column changes, because 100 is 1 hundreds.
   9780 has 7 hundreds
2. Take away 1 hundreds. Change that digit only. The other digits stay the same.
   7 - 1 = 6
3. Write the answer. Check that the other digits are the same.
   9680

Check. Check: 9680 + 100 = 9780.

Watch out. Adding or taking away a friendly number changes only one column, when no carry or exchange is needed.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Exchange in the tens column. The ones digit is too small, so exchange 1 ten for 10 ones.
   tens: 5 to 4; ones: 0 to 10
2. Subtract the ones column. Take the bottom digit from the top digit.
   10 - 6 = 4
3. Exchange in the hundreds column. The tens digit is too small, so exchange 1 hundred for 10 tens.
   hundreds: 7 to 6; tens: 4 to 14
4. Subtract the tens column. Take the bottom digit from the top digit.
   14 - 6 = 8
5. Subtract the hundreds column. Take the bottom digit from the top digit.
   6 - 4 = 2
6. Subtract the thousands column. Take the bottom digit from the top digit.
   9 - 1 = 8
7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   8284

Check. Check: 8284 + 1466 = 9750.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   7 + 6 = 13: Write 3 and carry 1 to the next column.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   8 + 0 + 1 = 9: Write 9. There is nothing to carry.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   1 + 0 = 1: Write 1. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   7 + 2 = 9: Write 9. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   9193

Check. Check: 9193 - 2006 = 7187.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   8 + 0 = 8: Write 8. There is nothing to carry.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   8 + 4 = 12: Write 2 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   7 + 1 + 1 = 9: Write 9. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   6 + 2 = 8: Write 8. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   8928

Check. Check: 8928 - 2140 = 6788.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   7 + 9 = 16: Write 6 and carry 1 to the next column.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   4 + 6 + 1 = 11: Write 1 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   2 + 5 + 1 = 8: Write 8. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   6 + 2 = 8: Write 8. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   8816

Check. Check: 8816 - 2569 = 6247.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Use the inverse operation to find the missing number.

1. Find what must be added. The missing number is the difference between the total and the known number.
   9783 - 4835 = 4948
2. Write the missing number. Check it fills the gap.
   4948

Check. Check: 4835 + 4948 = 9783.

Watch out. Addition and subtraction undo each other. Use the operation that undoes the one in the question.

Method. Change only the column that matches the number you add or take away.

1. Find the thousand digit in 8087. Only the thousand column changes, because 1000 is 1 thousands.
   8087 has 8 thousands
2. Add 1 thousands. Change that digit only. The other digits stay the same.
   8 + 1 = 9
3. Write the answer. Check that the other digits are the same.
   9087

Check. Check: 9087 - 1000 = 8087.

Watch out. Adding or taking away a friendly number changes only one column, when no carry or exchange is needed.

Method. Use the inverse operation to find the missing number.

1. Add the number that was taken away. Adding undoes the take away.
   7934 + 1868 = 9802
2. Write the missing number. Check it: taking away gives the answer.
   9802

Check. Check: 9802 - 1868 = 7934.

Watch out. Addition and subtraction undo each other. Use the operation that undoes the one in the question.

Method. Add column by column, starting with the ones. Carry any ten to the next column on the left.

1. Add the ones column. Add the digits, and the carried 1 if there is one.
   4 + 3 = 7: Write 7. There is nothing to carry.
2. Add the tens column. Add the digits, and the carried 1 if there is one.
   2 + 9 = 11: Write 1 and carry 1 to the next column.
3. Add the hundreds column. Add the digits, and the carried 1 if there is one.
   7 + 0 + 1 = 8: Write 8. There is nothing to carry.
4. Add the thousands column. Add the digits, and the carried 1 if there is one.
   5 + 3 = 8: Write 8. There is nothing to carry.
5. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   8817

Check. Check: 8817 - 3093 = 5724.

Watch out. Do not forget the carried 1 in the next column. Write the carried 1 small above the column.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Subtract the ones column. Take the bottom digit from the top digit.
   6 - 2 = 4
2. Exchange in the thousands column. The hundreds are 0, so exchange from further left: exchange 1 thousand for 10 hundreds.
   thousands: 7 to 6; hundreds: 0 to 10
3. Exchange in the hundreds column. The tens digit is too small, so exchange 1 hundred for 10 tens.
   hundreds: 10 to 9; tens: 2 to 12
4. Subtract the tens column. Take the bottom digit from the top digit.
   12 - 5 = 7
5. Subtract the hundreds column. Take the bottom digit from the top digit.
   9 - 0 = 9
6. Subtract the thousands column. Take the bottom digit from the top digit.
   6 - 3 = 3
7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   3974

Check. Check: 3974 + 3052 = 7026.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.

Method. Subtract column by column from the ones. When the top digit is too small, exchange from the column on the left.

1. Exchange in the tens column. The ones digit is too small, so exchange 1 ten for 10 ones.
   tens: 9 to 8; ones: 6 to 16
2. Subtract the ones column. Take the bottom digit from the top digit.
   16 - 7 = 9
3. Subtract the tens column. Take the bottom digit from the top digit.
   8 - 8 = 0
4. Exchange in the thousands column. The hundreds digit is too small, so exchange 1 thousand for 10 hundreds.
   thousands: 3 to 2; hundreds: 0 to 10
5. Subtract the hundreds column. Take the bottom digit from the top digit.
   10 - 3 = 7
6. Subtract the thousands column. Take the bottom digit from the top digit.
   2 - 1 = 1
7. Write the answer. Read the digits from the top: thousands, hundreds, tens and ones.
   1709

Check. Check: 1709 + 1387 = 3096.

Watch out. A zero cannot give a ten. Go left to the first column that is not zero, and exchange from there.