Ask a ten year old what 47 plus 38 is, and you can usually tell within two seconds which children have been taught mental maths and which have not. The taught child adds 40, then 7, then 1 more, and lands on 85. The untaught child tries to picture the sum written down, column by column, carrying digits in mid air, and gives up.

The difference is not intelligence and it is not speed. It is a small toolkit of methods. This article gives you the nine that matter most before secondary school, the ways to practise them at home without turning your kitchen into a classroom, and what to do if your child freezes the moment numbers appear.

1What mental maths actually is

Mental maths is calculating with numbers you have reshaped to be easier, not calculating the written method inside your head. That single distinction is the whole subject. The written method is designed for paper, moves right to left, and needs you to hold carried digits. Mental methods move left to right, work with round numbers, and hold far less in memory at once.

This matters because working memory is the bottleneck. Research on how mental arithmetic develops in primary school has found that verbal working memory is closely tied to how children’s arithmetic improves over time. A child juggling four carried digits has no capacity left for the actual sum. A child who breaks 47 plus 38 into 40 plus 30, then 7 plus 8, is holding two small things instead of five.

2Why mental maths matters more than speed

The real value of mental maths is that it builds number sense, which is the intuitive feel for how big numbers are and how they relate to each other. Number sense is a strong predictor of how children perform in maths overall. One study of primary pupils found that number sense and basic arithmetic ability were the routes through which general reasoning ability translated into actual maths performance.

In practical terms, a child with number sense notices when an answer is nonsense. They know that 8 times 7 cannot be 42, because 8 sevens must be more than 6 sevens. This is the skill that catches careless mistakes in exams, and it is worth far more marks than raw speed.

So please ignore the stopwatch. Speed arrives on its own once the methods are automatic. Chasing it first usually produces a child who guesses quickly and checks nothing.

3The 9 mental maths tricks every child should know by age 10

These nine cover almost everything a primary child meets. Teach one a week and say the method out loud each time, because naming the method is what makes it stick.

1. Make a ten

To add 8 plus 5, move 2 across from the 5 to make 10, then add the remaining 3. Ten is the friendliest number in the system, and children who bridge through it stop counting on their fingers.

2. Doubles and near doubles

Children learn doubles quickly, so use them. 7 plus 8 is double 7 plus 1, which is 15. 6 plus 7 is double 6 plus 1. One known fact unlocks two.

3. Add from the left

For 47 plus 38, do the tens first: 40 plus 30 is 70. Then the units: 7 plus 8 is 15. Then 70 plus 15 is 85. Starting with the big part means the child always has a rough answer in hand.

4. Round and adjust

To add 99, add 100 and take away 1. To subtract 198, subtract 200 and add 2 back. Any number close to a round number should be treated as the round number, then corrected.

5. Multiply by 5 the easy way

Halve the number, then multiply by 10. So 5 times 46 becomes 23 times 10, which is 230. Children find halving far easier than fives.

6. Multiply by 9 using 10

Multiply by 10, then subtract one lot. So 9 times 7 is 70 minus 7, which is 63. This removes the hardest column of the times table in one move.

7. Double for 4 and 8

To multiply by 4, double twice. To multiply by 8, double three times. So 8 times 15 is 30, then 60, then 120. No table needed.

8. Build percentages from 10 percent

Find 10 percent by moving the decimal point one place. Then 20 percent is that doubled, 5 percent is that halved, and 15 percent is 10 plus 5. This one trick covers most percentage questions a child will meet.

9. The reasonableness check

Before writing an answer, ask roughly how big it should be. 38 times 21 must be near 40 times 20, so around 800. If the child’s answer is 79 or 8000, they know instantly that something has gone wrong. This is the single most valuable habit on this list.

4How to practise without it feeling like homework

Practise in short bursts inside things you were doing anyway, and never with a timer running at first. Five minutes a day beats forty minutes on Sunday, because mental maths is a recall skill and recall is built by frequency, not duration.

The most effective format is asking rather than testing. In the car, at the supermarket, while cooking. Give a real number problem with a real purpose, let your child answer out loud, and then ask how they worked it out. That second question does most of the teaching, because it forces the child to name their method and notice when they used a slow one.

5Age by age, what to expect from 6 to 12

Children reach these stages at genuinely different times, so treat this as a map rather than a schedule.

Ages 6 to 7

Number bonds to 10 and then to 20, counting on and back, and recognising doubles. The aim is that small sums stop requiring fingers.

Ages 7 to 9

Bridging through ten, adding two digit numbers from the left, and the 2, 5 and 10 times tables becoming automatic. This is also the right window for round and adjust.

Ages 9 to 10

All times tables up to 12, doubling and halving fluently, and the reasonableness check becoming a habit rather than an instruction.

Ages 10 to 12

Percentages from 10 percent, simple fractions of amounts, and mental estimation before written work. By now the child should be choosing between methods rather than using one method for everything.

6Mistakes parents make with mental maths

The most damaging mistake is turning practice into a performance, usually by adding a timer or an audience. A child who is anxious loses working memory capacity, which is precisely the resource mental maths runs on, so anxiety does not just feel bad, it directly makes the child worse at the task.

Three others worth avoiding. Do not correct the answer before hearing the method, because the method is where the fixable problem lives. Do not ban fingers abruptly, since fingers fall away naturally once the number bonds are secure. And do not assume that a child who is slow is weak. Slow and accurate is a good position to be in. Fast and careless is much harder to repair.

If your child has genuinely lost confidence, the fastest repair is one to one attention, because the problem is nearly always a specific gap, one table, one method, one misunderstanding, that has been hidden by a class moving on. Training studies with primary aged children suggest that short, focused, targeted practice can shift maths performance in weeks rather than years.

What to do if your child freezes at mental maths

Start by finding the exact gap, because freezing is almost never general. It is one missing method or one shaky set of number bonds, and once the child hits it in a question, everything after it collapses. Sit with them, ask them to talk through a sum out loud, and listen for the moment the explanation stops making sense. That moment is the gap.

If you cannot find it, or if maths has become an argument in your house, a single 1 on 1 lesson will usually locate it faster than a term of classroom time, because a tutor teaching one child can hear every hesitation. That is what a free trial class is for. There is no cost and no obligation, and you will come away knowing precisely which of the nine tricks above your child is missing.