Use subtraction:
1945 - 1884:
Line up our numbers vertically:
1 | 9 | 4 | 5 | |
_ | 1 | 8 | 8 | 4 |
1 | 9 | 4 | 5 | |
_ | 1 | 8 | 8 | 4 | 1 |
Column 1: 5 - 4 = 1
14 | ||||
1 | 9 | 5 | ||
_ | 1 | 8 | 8 | 4 | 6 | 1 |
Column 2:
4 - 8 is < 0, we need to borrow 10.
Column 2: 10 + 4 - 8 = 6
8 | 14 | |||
1 | 5 | |||
_ | 1 | 8 | 8 | 4 | 0 | 6 | 1 |
Column 3:
Since we borrowed on the last column, we take it out of 9
Column 3: 9 - 1 - 8 = 0
8 | 14 | |||
1 | 5 | |||
_ | 1 | 8 | 8 | 4 | 0 | 0 | 6 | 1 |
Column 4: 1 - 1 = 0