My child keeps getting decimal division wrong. Where does it usually go wrong?
Mistakes tend to cluster in a few places. Finding the one your child makes helps more than doing dozens more questions.
The three most common mistakes
- Moving the decimal point in the divisor only, and forgetting to move the other number by the same number of places.
- Putting the decimal point in the wrong place in the answer, so it's out by 10 or 100 times.
- Not knowing they can add zeros and carry on dividing when the digits run out.
One worked through: 4.8 ÷ 0.6
Make the divisor a whole number: move the point in 0.6 one place right to get 6, and move the point in 4.8 one place right too, to get 48.
48 ÷ 6 = 8, so 4.8 ÷ 0.6 = 8.
You can explain it like this: how many 0.6s fit in 4.8? Making both numbers 10 times bigger doesn't change the answer.
Teach your child to check
- Estimate first: 4.8 ÷ 0.6 is roughly 5 ÷ 0.5, so the answer should be near 10, not 0.8 or 80.
- Check by multiplying: 8 × 0.6 = 4.8. Correct.
Is "careless" really careless?
Many so-called careless mistakes are steps that aren't secure yet. Children's attention and ability to check their own work are still developing, so simply saying "be careful" doesn't help much.
Instead, go through mistakes together, find the step that went wrong, and agree on a regular way of checking. Being called careless can feel like not being good enough. Pointing to a specific step shows them what to change.
