คำตอบ - Long subtraction
คำอธิบายทีละขั้นตอน
1. Rewrite the numbers from top to bottom, aligned by their place values
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . |
2. Subtract the numbers using long subtraction method
Subtract the numbers in the thousandths column from the top number:
6-5=1
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . | 1 |
Because the upper digit (1) in the hundredths column is too small to get a positive difference, borrow 1 from the digit (2) in the next number place which becomes (1) and get (11).
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . | 1 |
Subtract the numbers in the hundredths column from the top number:
11-4=7
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . | 7 | 1 |
Because the upper digit (1) in the tenths column is too small to get a positive difference, borrow 1 from the digit (3) in the next number place which becomes (2) and get (11).
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 2 | 11 | ||||||
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . | 7 | 1 |
Subtract the numbers in the tenths column from the top number:
11-2=9
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 2 | 11 | ||||||
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| . | 9 | 7 | 1 |
Subtract the numbers in the ones column from the top number:
2-1=1
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 2 | 11 | ||||||
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| 1 | . | 9 | 7 | 1 |
Subtract the numbers in the tens column from the top number:
8-7=1
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 2 | 11 | ||||||
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| 1 | 1 | . | 9 | 7 | 1 |
Subtract the numbers in the hundreds column from the top number:
7-7=0
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths |
| 2 | 11 | ||||||
| 1 | 11 | ||||||
| 7 | 8 | 3 | . | 2 | 1 | 6 | |
| - | 7 | 7 | 1 | . | 2 | 4 | 5 |
| 0 | 1 | 1 | . | 9 | 7 | 1 |
The solution is: 11.971
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