Watch a Year 5 child sit a timed paper and you'll see the same thing happen over and over. They've got an hour for fifty questions, plus a section that wants quick answers, and they're reaching for the side of the page to work out 6 times 8. They know the answer. They've known it since Year 3. But under pressure they freeze, and the pencil starts moving.
That's the whole game with 11 plus mental maths. The questions aren't hard. The clock is hard. A child who can do a sum in their head in two seconds gets four extra seconds for the next question. Across fifty questions that adds up to a different paper entirely.
So how do you actually train this stuff at home without making it miserable? Here's what I've learned working through it with my own son and watching what sticks.
Why mental maths is the make-or-break skill
Most 11+ maths papers don't reward clever methods. They reward speed and accuracy on basic arithmetic. Trick questions usually sit on top of fast number work. If it takes your child 30 seconds to multiply 7 by 8, they won't solve a multi-step word problem inside 90 seconds. Something has to give, and it's usually the back half of the paper.
This catches out children who are bright but slow. Their maths is fine, sometimes excellent. They lose marks because they ran out of time on the second half of the paper. If you've ever looked at a results sheet and seen a sharp drop-off after question 35, you know exactly what I mean.
The good news is mental maths is one of the most trainable parts of the 11+. Unlike reading comprehension, which builds over years, you can move the needle on mental arithmetic in a few weeks of consistent short practice.
Build the number bond floor first
Before anything fancy, your child needs total fluency with number bonds to 10, 20 and 100. That means knowing instantly that 7 and 3 make 10, that 14 and 6 make 20, that 73 and 27 make 100. No counting, no fingers, no thinking. Just retrieval.
Once that's solid, push it into decimals. What pairs with 0.4 to make 1? What pairs with 0.65 to make 1? These come up constantly in 11+ questions about change, weight and percentages, and children who haven't drilled them lose seconds every time.
A two-minute warm-up at the kitchen table works better than a twenty-minute session once a week. You're trying to build automatic recall, not understanding. They already understand it. They just need it to come out faster than thinking.
Times tables that pull more than their weight
Everyone tells you to learn the times tables. Fewer people tell you which ones earn the most marks in an 11+ paper. From what I've seen, the heavy lifters are the 6s, 7s, 8s and 12s. Children find these the hardest, which is exactly why they show up most.
Test backwards as well as forwards. Don't just ask "what's 7 times 8". Ask "what divides into 56" and "what's 56 divided by 7". A child who can only answer in one direction will stumble on division questions even though they know the multiplication cold.
And don't forget squares. Knowing that 11 squared is 121, 12 squared is 144 and 15 squared is 225 unlocks dozens of area, sequence and reasoning questions. This single piece of knowledge punches well above its weight.
The five techniques worth drilling
A handful of mental shortcuts give you huge return for the time spent learning them.
The first is doubling and halving. To multiply by 4, double twice. To multiply by 50, halve and then multiply by 100. To find 25 percent of anything, halve it twice. Children who internalise this stop being scared of percentages.
The second is the nines trick. To multiply any number by 9, multiply by 10 and subtract the original. So 9 times 7 becomes 70 minus 7, which is 63. It's faster than reciting the nine times table, and it makes the bigger nines (9 times 14, 9 times 23) trivial.
The third is the bridging technique for addition. To add 38 and 47, your child rounds 38 up to 40, adds 47 to get 87, then takes the 2 back off. They land at 85 in their head with no carrying or borrowing.
The fourth is rounding to estimate. Before working out anything complex, get a rough answer first. If the multiple-choice options are 234, 1,180 and 12,400, you usually don't need to calculate at all. You just need to know which order of magnitude you're in.
The fifth is the 25 and 75 shortcut for percentages. 25 percent is a quarter. 75 percent is three quarters. Children who learn these as fractions stop trying to do percentage sums the hard way.
How to practise without turning your child off maths
Five minutes a day, six days a week, is more powerful than half an hour at the weekend. The brain consolidates this kind of recall through frequency, not duration. If you only have five minutes in the car on the school run, that's plenty.
Use games where you can. There's a reason every primary teacher has a stack of dice in the cupboard. Roll two dice and multiply. Roll three and add. Roll four and find the highest possible total. It feels like play and it builds the same retrieval muscle as flashcards.
Avoid timed pressure at first. If your child is making errors, slow down and rebuild accuracy before adding the clock. A child who learns to do mental maths wrongly under pressure has built a bad habit that takes weeks to unpick. Build slow, then build fast.
And do it out loud, especially with younger children. Saying "six eights are forty-eight" cements the answer in a way that silent repetition doesn't. You're hearing it, saying it and processing it all at once.
The mistake I made early on
When my son was in Year 4 I bought a thick book of mental arithmetic and made him do a page a day. He hated it. The pages were dense and the format was joyless. After about two weeks he'd dug his heels in and decided he was bad at maths. He wasn't. The format was.
What worked instead was short bursts of verbal practice, mixed with games, and graded so he could feel himself getting quicker. You want a child who knows they're improving. The book was hiding that progress in a sea of grey questions.
If you've got a child who's resistant, drop the worksheets entirely for a fortnight and just do quick verbal practice. You'll often find the underlying ability was always there. What was missing was the willingness to engage with it.
Frequently asked questions
How fast should my Year 5 be at mental arithmetic? Aim for around two seconds for any times table fact, four to five seconds for a two-digit addition or subtraction, and under ten seconds for a simple percentage or fraction. If they're consistently slower than that on the basics, the paper-based questions will run out of time before they finish.
Should I use an app or do it verbally? Both have their place. Apps are good for repetition and tracking, but verbal practice with a parent is harder to fake and builds confidence faster. A mix works best, with fifteen minutes of an app a few times a week plus short verbal bursts in the car or at breakfast.
My child knows the maths but freezes in tests. Is that mental maths or anxiety? Often it's both, and they feed each other. A child who isn't confident in their recall feels exposed under time pressure, which makes recall slower, which deepens the anxiety. Fixing the recall first usually softens the panic, because the child has something solid to hold onto.
Are the mental maths sections the same in GL and CEM papers? Not exactly. GL papers tend to have a separate mental arithmetic section with shorter time per question. CEM-style papers and most regional tests mix mental maths into the main paper, but the time pressure is just as real. Either way, the underlying skill is the same: quick, accurate arithmetic without paper.
If you want to see how your child's mental maths actually stacks up against what the 11+ will demand of them, readyfor11.co.uk gives you a free benchmark you can act on. No platform, no subscription, just an honest read.