Column subtraction: watch it solved step by step

Subtract in columns, borrowing across zeros when needed. Level: KS2 / KS3. Type any problem of this kind and the Lab works it out and animates every move, with a plain-words explanation of why.

Worked example: 1000 - 1

1. Set out the subtraction. Write the smaller number under the bigger one, ones under ones. Subtract one column at a time from the right. If a top digit is too small, we borrow (exchange) from the next column.
2. Borrow for the ones column. 0 is smaller than 1, so we cannot subtract yet. Borrow: take 1 from the thousands (leaving 0) and give 10 to the hundreds (now 10); then take 1 from the hundreds (leaving 9) and give 10 to the tens (now 10); then take 1 from the tens (leaving 9) and give 10 to the ones (now 10). The ones digit is now 10.
3. Subtract the ones column. 10 - 1 = 9. Write 9.
4. Subtract the tens column. 9 - 0 = 9. Write 9.
5. Subtract the hundreds column. 9 - 0 = 9. Write 9.
6. Subtract the thousands column. 0 - 0 = 0. Write 0.
7. The answer. 1000 − 1 = 999. (Check: 999 + 1 = 1000.)

Answer: 999

Practise column subtraction with problems the Lab marks for you.