Here we will show you step-by-step how to calculate 21 minus 28 using the long subtraction method.
Before we continue, note that 21 is called the minuend and 28 is called the subtrahend.
To solve the problem 21 minus 28 using long subtraction, we first put the largest number on top and the smallest number at the bottom like this:
| 2 | 8 | |||||||
| - | 2 | 1 | ||||||
Then you subtract the ones digits (8 - 1 = 7) like this:
| 2 | 8 | |||||||
| - | 2 | 1 | ||||||
| 7 |
Next you subtract the tens digits (2 - 2 = 0) like this:
| 2 | 8 | |||||||
| - | 2 | 1 | ||||||
| 0 | 7 |
Note that since the minuend is smaller than the subtrahend, the answer is a negative number.
And that's it. The problem with the answer is displayed below:
21 - 28 = -7
Long Subtraction Calculator
Here you can enter another subtraction problem for us to explain and solve using the long subtraction method: