# Column subtraction: 3 digit, with borrowing

**Introduced in the Year 4 curriculum as:** "*Add and subtract numbers with up to 4 digits using the formal written methods of columnar addition and subtraction where appropriate*"

When doing column subtraction, sometimes you have to borrow from the tens digit and then from the hundreds digit, too.

Press SHOW/HIDE if you need to do jottings.

Example 1:

2 is __too small__ to subtract 9 from, so we borrow from the 5 in the 10s column.

2 becomes 12 because it borrows 1 from the 10s column. 12 subtract 9 is 3.

The 5 becomes 4 because we borrowed one from 5. 4 subtract 3 is 1.

Then we subtract the hundreds digits as normal. 4 subtract 1 is 3.

Example 2:

2 is __too small__ to subtract 4 from, so we borrow from the 5 in the 10s column.

2 becomes 12 because it borrows 1 from the 10s column. 12 subtract 4 is 8.

The 5 becomes 4 because we borrowed one from 5.

4 is __too small__ to subtract 6 from, so we borrow from the 7 in the 100s column.

4 becomes 14 because it borrows 1 from the 10s column. 14 subtract 6 is 8.

The 7 becomes 6 because we borrowed one from 7. 6 subtract 3 is 3.

Example 3:

4 is __too small__ to subtract 6 from, so we try to borrow from the 10s column.

We __cannot__ borrow from 0, so first we borrow from the 5 in the 100s column. The 5 becomes 4 because we borrowed one from 5.

The 0 becomes 10 because we have borrowed one from the 100s column.

Now, we can borrow from the 10s column. 4 in the ones column becomes 14.

14 subtract 6 is 8. The 10 becomes 9 because we borrowed from it.

9 subtract 2 is 7 and 4 subtract 3 is 1.