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There are two common methods for subtracting numbers arranged in columns - the Decomposition Method which most parents and teachers will have learned in school, and a second method called the Equal Addition Method. In the end both give the same answer, but the equal addition method tends to be the easier to explain and learn thanks to its simplicity.
When using the equal addition method, the bottom number is subtracted from the top number in each column, starting in the units column and working left through the tens, hundreds, and so on. If the bottom number is larger than the top number in a column, we just add 10 to the top number and add 1 to the bottom number in the next column to the left as shown in the example below:
| 7 1 6 - 1 1 8 |
| 5 8 |
Level 1 - 2 digit minus 2 digit, no borrow.
Level 2 - 3 digit minus 3 digit, no borrow.
Level 3 - 2 digit minus 2 digit, with borrow.
Level 4 - 3 digit minus 3 digit, with borrow.
Level 5 - 4 digit minus 4 digit, with borrow.
Level 6 - 5 digit minus 5 digit, with borrow.
press F5 to repeat a level with new numbers.
For printable PDF column subtraction worksheets for each of the levels mentioned above click here:
Alternatively, you can enter numbers yourself below to see how they one is subtracted from the other using the equal addition method of column subtraction.
| 3 1 9 - 1 5 3 |
Look at the units column.
We have 9 - 3 = 6, so write 6 at the bottom of the units column.
| 3 1 9 - 1 5 3 |
| 6 |
Look at the tens column.
1 is less than 5 so we add 10 to the 1 in the tens column giving us 11, and at the same time add 1 to be subtracted later from the hundreds column.
(Adding 10 to the tens column is actually adding 100 to the final answer. Adding 1 to be subtracted from the hundreds column is actually subtracting 100 from the final answer. Therefore since 100 - 100 = 0, we have not changed the final answer, just made it easier to calculate.)
Now we have 11 - 5 = 6, so write 6 at the bottom of the tens column.
| 3 1 1 9 - 1 1 5 3 |
| 6 6 |
Look at the hundreds column.
We have 3 - 1 - 1 = 1, so write 1 at the bottom of the hundreds column.
| 3 1 1 9 - 1 1 5 3 |
| 1 6 6 |
So using the equal addition method, we have worked out that 319 - 153 = 166
Press F5 for another example.
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