Mental maths practice, by age

What mental maths is for

A child who can hold 70 + 15 in their head has attention left over for the actual problem. That is the point of it. Speed matters less than it looks: a child who knows why 99 + 45 is 144 will get there quickly anyway, and will still get there on the day they are nervous.

Some schools do test raw recall. In England, every Year 4 child sits a times-tables check on screen, with a few seconds for each question1. Recall and tricks work together: the tricks below lean on a small set of facts you know by heart, like 4 × 25 = 100.

Ages 5 to 7 (Class 1 and 2): make ten

Ten is the friendliest number there is. When a sum crosses ten, borrow from the second number to fill the first one up to ten, then add what is left. It replaces counting on fingers with one small, reliable move.

Practise the pairs that make ten (1 and 9, 2 and 8, and so on) until they are instant. Everything else here is built on them.

Ages 7 to 9 (Class 3 and 4): tens first, round and fix

On paper, children add the ones first. In your head it is easier the other way round: tens first, then ones, because the big part of the answer arrives first and the rest is a small correction.

The second trick is rounding. 99 is awkward, 100 is easy. Add 100, then give back the 1 you borrowed. The same works for taking away: 63 − 28 is 63 − 30 = 33, then add back the 2 you took too many.

Ages 9 to 11 (Class 5 and 6): multiply by splitting

Multiplying a two-digit number in your head is two easy multiplications and an addition. Split the bigger number into tens and ones, multiply each part, then put them together.

Three shortcuts are worth knowing by heart at this age:

• × 5 is × 10 and then halve: 48 × 5 = 480 ÷ 2.
• × 25 means looking for fours, because 4 × 25 = 100: 16 × 25 = 4 × 100.
• × 99 is × 100 minus one lot: 99 × 7 = 700 − 7.

Ages 11 and up (Class 7 and 8): squares and percentages

Older children can use a little algebra in their heads. Two numbers either side of a round number multiply to that number squared, minus a small square:

Squares of numbers ending in 5 have their own shortcut (take the tens digit, multiply by the next number up, write 25 after it), and percentages break into tens and fives: 15% is 10% plus half of that again. This is the level where mental maths starts to feel like the olympiad kind of maths: seeing structure instead of grinding.

Making it a habit

1. Five minutes, most daysA short set each day does more than a long one at the weekend. Stop while it still feels easy to start again tomorrow.
2. Ask how, not just what“How did you get 85?” Hearing the method out loud is how you catch a trick that only works by luck.
3. Mix old tricks with new onesOnce a trick is solid, mix it in with the others. In one study, students who practised mixed problem types did better a week later than those who practised one type at a time2.
4. Use real numbersShopping totals, change from ₹500, cricket scores, how many days to a birthday. Numbers that matter get worked out.

Questions parents ask

Should my child learn times tables by heart?

Yes, up to 10 × 10 at least, and 12 × 12 if their school expects it. Facts you don’t have to work out leave room for the problem in front of you. Learn them alongside the tricks, not instead of understanding.

What about abacus and Vedic maths classes?

Both can build real fluency and confidence. The test is whether your child can explain why a trick works. If they can, it will last; if it is only a routine, it tends to fade when the numbers look different.

My child is slow at mental maths. Is that a problem?

Not on its own. Slow and sure beats fast and guessing. If the same kind of sum keeps going wrong, look for the missing step behind it; our guide on why a child struggles with maths shows how.