Method used below: column subtracting, from right to left (traditional)
Stack the numbers on top of each other.
The ones digits line up in the first column from the right.
The tens digits line up in the next column to the left.
And so on...
Subtract column by column; start from the column on the right
Subtract the digits in the ones column:
8 - 0 = 8.
8 is the ones digit.
Write it down at the base of the ones column.
Subtract the digits in the tens column:
1 - 7 = ?
The second digit is larger than the first.
Borrow from the next column to the left.
The borrowing is a two step process:
Subtract 1 from the top digit in the column of the hundreds: 2 - 1 = 1.
Cross out the top digit you've borrowed 1 from: 2.
Write the answer above that digit: 1.
When borrowing, 1 hundred = 10 tens.
Add 10 to the top digit in the column of the tens: 10 + 1 = 11.
After borrowing, the subtraction has become:
11 - 7 = 10 + 1 - 7 = 10 + 1 - 7 = 1 + (10 - 7) = 1 + 3 = 4.
4 is the tens digit.
Write it down at the base of the tens column.
Subtract the digits in the hundreds column:
2 1 - 1 = 0.
0 is the hundreds digit.
Write it down at the base of the hundreds column.
Leading zeros
When leading zeros occupy the most significant digits of a natural number, they could be left blank and the numeric value stays the same:
048 = 48
The answer will be negative (less than zero):
170 - 218 = - 48
Final answer:
- 218 + 170 = - 48