คำตอบ - Long subtraction
5.7
คำอธิบายทีละขั้นตอน
1. Rewrite the numbers from top to bottom, aligned by their place values
| Place value | ones | . | tenths |
| 9 | . | 7 | |
| 1 | . | 1 | |
| - | 2 | . | 9 |
| . |
2. Subtract the numbers using long subtraction method
Because the upper digit (7) in the tenths column is too small to get a positive difference, borrow 1 from the digit (9) in the next number place which becomes (8) and get (17).
| Place value | ones | . | tenths |
| 8 | 17 | ||
| 9 | . | 7 | |
| 1 | . | 1 | |
| - | 2 | . | 9 |
| . |
Subtract the numbers in the tenths column from the top number:
17-1-9=7
| Place value | ones | . | tenths |
| 8 | 17 | ||
| 9 | . | 7 | |
| 1 | . | 1 | |
| - | 2 | . | 9 |
| . | 7 |
Subtract the numbers in the ones column from the top number:
8-1-2=5
| Place value | ones | . | tenths |
| 8 | 17 | ||
| 9 | . | 7 | |
| 1 | . | 1 | |
| - | 2 | . | 9 |
| 5 | . | 7 |
The solution is: 5.7
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