Vertically align numbers with Larger Number on top:
| 4 | 0 | 2 | |
| − | 1 | 5 |
Subtract using place value:
| Hundreds | Tens | Ones | |
|---|---|---|---|
| 9 | |||
| 3 | 10 | 12 | |
| 402 | 4 | 0 | 2 |
| 15 | 1 | 5 | |
| Difference | 3 | 8 | 7 |
Column traversal from right to left
Ones column:
Ones column:
- Since 2 is less than 5, we have to borrow 1 from the Tens column
- As a result, 2 becomes 12, and 12 − 5 = 7
- The 0 in the Tens column becomes 9 after borrowing 1 from its regrouped value of 10
Tens column:
- 9 − 1 = 8
- Because it was the first nonzero digit to the left of the 2 in the Ones column, the 4 in the Hundreds column became 3 after 1 was borrowed for the purpose of regrouping the 0 in the Tens column (borrowing across a 0)
Hundreds column:
- 3 − 0 = 3
| 9 | |||
| 3 | 10 | 12 | |
| 4 | 0 | 2 | |
| − | 1 | 5 | |
| 3 | 8 | 7 |
Therefore, the Difference between 402 and 15 is 387
Check computation by comparing Larger Number and the Sum of Difference and Smaller Number:
| 1 | 1 | ||
| 3 | 8 | 7 | |
| 1 | 5 | ||
| 4 | 0 | 2 |
Sum of Difference and Smaller Number = 402
Sum of Difference and Smaller Number = Larger Number (402 = 402) ✓
