Vertically align numbers with Larger Number on top:
| 1 | 0 | 0 | . | 0 | |
| − | 8 | 9 | . | 5 |
Subtract using place value:
| Hundreds | Tens | Ones | Tenths | ||
|---|---|---|---|---|---|
| 9 | 9 | ||||
| 0 | 10 | 10 | 10 | ||
| 100 | 1 | 0 | 0 | . | 0 |
| 89.5 | 8 | 9 | . | 5 | |
| Difference | 1 | 0 | . | 5 |
Column traversal from right to left
Tenths column:
- Since 0 is less than 5, we have to borrow 1 from the Ones column
- As a result, 0 becomes 10, and 10 − 5 = 5
- The 0 in the Ones column becomes 9 after borrowing 1 from its regrouped value of 10
Ones column:
- 9 − 9 = 0
- The 0 in the Tens column became 9 after 1 was borrowed from its regrouped value of 10 for the purpose of regrouping the 0 in the Ones column
Tens column:
- 9 − 8 = 1
- Because it was the first nonzero digit to the left of the 0 in the Tenths column, the 1 in the Hundreds column became 0 after 1 was borrowed for the purpose of regrouping the 0 in the Tens column (borrowing across 0s)
Hundreds column:
- 0 − 0 = 0
Note: Leading zero is dropped
| 9 | 9 | ||||
| 0 | 10 | 10 | 10 | ||
| 1 | 0 | 0 | . | 0 | |
| − | 8 | 9 | . | 5 | |
| 1 | 0 | . | 5 |
Therefore, the Difference between 100 and 89.5 is 10.5
Check computation by comparing Larger Number and the Sum of Smaller Number and Difference:
| 1 | 1 | 1 | |||
| 8 | 9 | . | 5 | ||
| 1 | 0 | . | 5 | ||
| 1 | 0 | 0 | . | 0 |
Sum of Smaller Number and Difference = 100 (trailing zero is dropped)
Sum of Smaller Number and Difference = Larger Number (100 = 100) ✓
