10 Mental Math Tricks Every Kid Should Know
A child who can juggle numbers in their head walks into every maths lesson with confidence. These ten tricks turn “hard” calculations into games — practise one a week, out loud, anywhere.
Why mental math matters
Mental math isn't about speed for its own sake. It builds number sense — the feeling that numbers can be taken apart and put back together. That feeling is what makes fractions, percentages and algebra click later on.
The 10 tricks
- Make ten first: 9 + 6 → take 1 from the 6 → 10 + 5 = 15.
- Adding 9 = add 10, take 1: 47 + 9 → 57 − 1 = 56.
- Add left to right: 34 + 25 → 30+20=50, 4+5=9 → 59. The way heads work, not paper.
- Subtract by counting up: 62 − 58 → from 58 to 62 is 4. No borrowing needed.
- Doubles are anchors: know 6+6, then 6+7 is “double plus one”.
- ×4 = double twice: 16 × 4 → 32 → 64.
- ×5 = ×10 then half: 18 × 5 → 180 → 90.
- The 9s finger trick: for 9 × 4, fold the 4th finger — 3 and 6 → 36.
- ×11 magic (2-digit): 23 × 11 → put 2+3 in the middle → 253.
- Round, then fix: 198 + 47 → 200 + 47 − 2 = 245.
How to practise without tears
Five minutes a day, always out loud, never as a test. Ask “how did you get it?” — explaining locks in the trick. Shopping totals, cooking measures and car-ride challenges are perfect. Adaptive app practice adds instant feedback when you're busy.
Adaptive mental-math practice that adjusts to your child — offline, safe and free.
One trick a week. In ten weeks your child owns a toolbox that makes every maths lesson lighter — and numbers a little bit magical.
Frequently asked questions
At what age should kids start mental math?
From ages 5–6 with number bonds to 10 (“make ten first”). Tricks involving multiplication fit naturally from age 7 up, alongside the times tables.
My child counts on fingers — is that bad?
Not at all. Finger counting is a healthy stage that builds number sense. The tricks above gradually replace it, without ever forbidding it.
How can we practise mental math in daily life?
Estimate the shopping total, double a recipe together, play “how far to 100?” in the car. Five spoken minutes a day beat any worksheet.