Subtract Three-Digit Numbers With Borrowing

Subtract 284 from 731 with borrowing in both the ones column and the tens column to get 447.

Example

sub-731-284.math

   731
-  284
------

step: ones: 1 < 4, borrow from tens
step: borrow: tens 3 -> 2, ones 1 -> 11
step: ones: 11 - 4 = 7, write 7
step: tens: 2 < 8, borrow from hundreds
step: borrow: hundreds 7 -> 6, tens 2 -> 12
step: tens: 12 - 8 = 4, write 4
step: hundreds: 6 - 2 = 4, write 4
step: 731 - 284 = 447

chained-borrowing A subtraction problem may require borrowing in more than one column. Each borrow reduces the column to the left by 1 and adds 10 to the current column. Handle borrows from right to left, one column at a time.