Column subtraction practice
Column subtraction takes away one column at a time, exchanging from the next column when the top digit is too small. Noggli practises it from 67 − 5 up to decimals.
What your child practises
- Year 2subtract ones from a two-digit number
- Year 3subtract numbers with up to three digits
- Year 4subtract numbers with up to four digits using columns
- Year 5subtract whole numbers with more than four digits
- Year 6subtract decimals with up to two decimal places
Mix-ups Noggli looks out for
- Takes the smaller digit from the bigger one in each column instead of exchanging
Exchanging (borrowing)
In 52 − 27, you cannot take 7 from 2, so exchange one ten for ten ones: the 5 tens become 4 and the 2 ones become 12. Now 12 − 7 = 5 and 4 − 2 = 2, so the answer is 25.
The most common slip is taking the smaller digit from the bigger one in each column (7 − 2 = 5 and 5 − 2 = 3, giving 35). Noggli looks out for exactly this.
Where it fits
Simple take-aways are Year 2, three-digit numbers Year 3, four-digit column subtraction Year 4, bigger numbers Year 5 and decimals Year 6.
Helping at home
- Check by adding: 25 + 27 should give 52.
- Use coins to exchange a 10p for ten 1p coins.
- Always start from the ones column.
Made for children who worry about getting it wrong
A clue, not a cross
A wrong answer gets a clue and another go. A second miss shows how it works, step by step.
No clock
Nothing counts down. Confidence first, speed follows on its own.
The right level
After a few questions Noggli knows where your child is, and every question after that adapts.
Related practice
Questions parents ask
What is column subtraction?
A written method for subtracting where numbers are lined up by place value and subtracted one column at a time, starting from the ones, exchanging from the next column when needed.
Why does my child get subtraction answers that are too big?
Usually because they are taking the smaller digit from the larger in every column instead of exchanging. Noggli spots this pattern and lists it in your report if it keeps happening.
Is borrowing the same as exchanging?
Yes. Schools now usually say exchanging, because one ten is swapped for ten ones.
Practise this every day, at the right level
Noggli works out where your child is in every topic and adjusts each question to suit. Free, with no timers, no scores and no child accounts.