These 20 mental math tricks for kids turn sums that look hard into steps a child can do in their head. Each trick comes with one worked example, and they are grouped by addition, subtraction, multiplication, division and percentages. You will also find a guide to which trick suits which grade and a five-minute daily routine.
How to use these mental math tricks for kids
Do not teach all 20 at once. Pick one trick, show the example, then try three or four similar sums together. Move on only when your child can explain the trick back to you in their own words.
Ask your child to say each step out loud. Hearing the thinking tells you where it goes wrong, and it helps the method stick.
Addition tricks
1. Make ten first
Split the second number so the first one reaches 10. Example: 8 + 6. Take 2 from the 6 to make 10, then add the 4 that is left. 10 + 4 = 14.
2. Use doubles and near doubles
If the numbers are next to each other, double the smaller one and add 1. Example: 7 + 8 is double 7 plus 1, so 14 + 1 = 15.
3. Add the tens, then the ones
Keep the first number whole and add the second in two parts. Example: 47 + 35. First 47 + 30 = 77, then 77 + 5 = 82.
4. Round up and adjust
When a number is close to a ten, round it up and take the extra away at the end. Example: 58 + 29. Add 30 to get 88, then subtract 1. The answer is 87.
Subtraction tricks
5. Count up instead of taking away
Find the gap by counting from the smaller number to the bigger one. Example: 82 - 67. From 67 to 70 is 3, and from 70 to 82 is 12. Then 3 + 12 = 15.
6. Subtract a round number and add back
Example: 73 - 19. Subtract 20 to get 53. You took away 1 too many, so add 1 back. The answer is 54.
7. Subtract in parts
Take away the tens first, then the ones in easy steps. Example: 64 - 27. First 64 - 20 = 44. Then take 4 to reach 40, and the last 3 to reach 37.
8. Subtract from 1000 without borrowing
Take every digit from 9, except the last one, which you take from 10. Example: 1000 - 364. 9 - 3 = 6, 9 - 6 = 3, and 10 - 4 = 6. The answer is 636.
Multiplication tricks
9. Multiply by 4: double, then double again
Example: 4 x 23. Double 23 to get 46. Double 46 to get 92.
10. Multiply by 5: times 10, then halve
Example: 5 x 48. First 10 x 48 = 480. Half of 480 is 240.
11. Multiply by 9: times 10, then take one lot away
Example: 9 x 16. First 10 x 16 = 160. Take away one 16, and 160 - 16 = 144.
12. Multiply a two-digit number by 11
Add the two digits and put the sum between them. Example: 11 x 34. 3 + 4 = 7, so the answer is 374.
If the sum is 10 or more, carry the 1 to the first digit. For 11 x 58, 5 + 8 = 13. Write the 3 in the middle and add 1 to the 5, which gives 638.
13. Break the number apart
Split the bigger number into tens and ones, multiply each part and add. Example: 7 x 14. 7 x 10 = 70 and 7 x 4 = 28. Then 70 + 28 = 98.
14. Halve one, double the other
Halving one number and doubling the other keeps the answer the same. Example: 16 x 25 becomes 8 x 50, which becomes 4 x 100. The answer is 400.
Division tricks
15. Divide by 4: halve, then halve again
Example: 96 ÷ 4. Half of 96 is 48. Half of 48 is 24.
16. Divide by 5: double, then divide by 10
Example: 130 ÷ 5. Double 130 to get 260. Then 260 ÷ 10 = 26.
17. Split into friendly parts
Break the number into pieces that are easy to divide. Example: 84 ÷ 7. Split 84 into 70 and 14. 70 ÷ 7 = 10 and 14 ÷ 7 = 2. Then 10 + 2 = 12.
Percentage and fraction tricks
18. Find 10% first
To find 10%, divide by 10. Build other percentages from it. Example: 15% of 80. 10% of 80 is 8, and 5% is half of that, which is 4. Then 8 + 4 = 12.
19. Flip the percentage
A percent of B is the same as B percent of A, so choose the easier one. Example: 8% of 50 is the same as 50% of 8. Half of 8 is 4.
20. Fraction of a number: divide by the bottom, multiply by the top
Example: three quarters of 48. First 48 ÷ 4 = 12, then 12 x 3 = 36.
Which trick suits which grade
This is a rough guide. A child is ready for a trick when the skill underneath it is secure, whatever grade they are in.
| Tricks | Suitable grade | What your child should know first |
|---|---|---|
| 1 and 2: make ten, doubles | Grades 1 to 2 | Number pairs that make 10 |
| 3 and 4: adding two-digit numbers | Grades 2 to 3 | Tens and ones |
| 5, 6 and 7: subtraction | Grades 2 to 3 | Counting on in tens |
| 8: subtracting from 1000 | Grades 3 to 4 | Hundreds, tens and ones |
| 9, 10 and 11: multiplying by 4, 5 and 9 | Grades 3 to 4 | Doubling, halving and the 10 times table |
| 12, 13 and 14: bigger multiplication | Grades 4 to 5 | Times tables up to 10 |
| 15, 16 and 17: division | Grades 4 to 5 | Division as the reverse of multiplication |
| 18, 19 and 20: percentages and fractions | Grades 5 to 7 | What a fraction and a percent mean |
How to practise in five minutes a day
Five minutes a day is enough if you keep it regular. You need nothing but a scrap of paper to note the sums. Here is a simple routine.
- Minute 1: warm up. Ask five quick facts your child already knows, such as doubles or number pairs to 10.
- Minutes 2 and 3: trick of the week. Give four sums that use one trick. Ask your child to say the steps out loud.
- Minute 4: mixed review. Give three sums from tricks learned in earlier weeks, without saying which trick to use.
- Minute 5: your child sets the sum. Let them give you a question and check your answer. Get one wrong on purpose now and then and see if they catch it.
A few things keep the habit going:
- Attach it to something that already happens every day, such as breakfast or the drive to school.
- Stay with one trick for a full week before adding another.
- Aim for the right answer first. Speed follows on its own.
- Use real moments: adding up items on a shopping list, sharing snacks equally, working out how many minutes until bedtime.
Tricks work best on top of solid basics. If a trick will not stick, check the skill in the table above first. Trouble with trick 10, for example, usually means halving needs more practice, not the trick itself.
If your child would enjoy more of a challenge, or needs the basics rebuilt with patience, Core Minds Academy offers live online math classes, 1:1 or in pairs. You can book a free trial class to see if it suits your child, or look through our other courses.
