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 | ten thousandths |
| 2 | 1 | 8 | ||||||
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . |
Put zeros in the blank number places:
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . |
2. Subtract the numbers using long subtraction method
Because the upper digit (0) in the ten thousandths column is too small to get a positive difference, borrow 1 from the number to the left (8.000) which becomes (7.999) and get (10).
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . |
Subtract the numbers in the ten thousandths column from the top number:
10-0-3=7
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . | 7 |
Subtract the numbers in the thousandths column from the top number:
9-3=6
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . | 6 | 7 |
Subtract the numbers in the hundredths column from the top number:
9-3=6
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . | 6 | 6 | 7 |
Subtract the numbers in the tenths column from the top number:
9-8=1
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| . | 1 | 6 | 6 | 7 |
Subtract the numbers in the ones column from the top number:
7-7=0
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| 0 | . | 1 | 6 | 6 | 7 |
Because the upper digit (1) in the tens 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 | ten thousandths |
| 1 | 11 | |||||||
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| 0 | . | 1 | 6 | 6 | 7 |
Subtract the numbers in the tens column from the top number:
11-9=2
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 1 | 11 | |||||||
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| 2 | 0 | . | 1 | 6 | 6 | 7 |
Subtract the numbers in the hundreds column from the top number:
1-1=0
| Place value | hundreds | tens | ones | . | tenths | hundredths | thousandths | ten thousandths |
| 1 | 11 | |||||||
| 7 | 9 | 9 | 9 | 10 | ||||
| 2 | 1 | 8 | . | 0 | 0 | 0 | 0 | |
| - | 1 | 9 | 7 | . | 8 | 3 | 3 | 3 |
| 0 | 2 | 0 | . | 1 | 6 | 6 | 7 |
The solution is: 20.1667
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