คำตอบ - Long subtraction
0.8
คำอธิบายทีละขั้นตอน
1. Rewrite the numbers from top to bottom, aligned by their place values
| Place value | tens | ones | . | tenths | hundredths |
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| . |
2. Subtract the numbers using long subtraction method
Subtract the numbers in the hundredths column from the top number:
9-9=0
| Place value | tens | ones | . | tenths | hundredths |
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| . | 0 |
Because the upper digit (0) 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 (10).
| Place value | tens | ones | . | tenths | hundredths |
| 8 | 10 | ||||
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| . | 0 |
Subtract the numbers in the tenths column from the top number:
10-2=8
| Place value | tens | ones | . | tenths | hundredths |
| 8 | 10 | ||||
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| . | 8 | 0 |
Subtract the numbers in the ones column from the top number:
8-8=0
| Place value | tens | ones | . | tenths | hundredths |
| 8 | 10 | ||||
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| 0 | . | 8 | 0 |
Subtract the numbers in the tens column from the top number:
9-9=0
| Place value | tens | ones | . | tenths | hundredths |
| 8 | 10 | ||||
| 9 | 9 | . | 0 | 9 | |
| - | 9 | 8 | . | 2 | 9 |
| 0 | 0 | . | 8 | 0 |
The solution is: 0.8
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