Mental Math Practice
Choose your operations and level, then work through the problems: a set of 20 to measure time and accuracy, or a 60-second timer to get as many right answers as you can. Your record stays on your device.
- 4 operations
- 4 levels
- 60-second challenge
- Free, no sign-up
100% private — Everything is processed directly in your browser: your files, voice, and image are never sent to Chatzam's servers.
How to practice mental math
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Choose the operations and level
Check addition, subtraction, multiplication or division, then pick the level: easy, medium, hard or expert.
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Start a set or the timer
A set of 20 problems to work on accuracy, or 60 seconds to work on speed.
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Type your answer
With your keyboard or the on-screen number pad: as soon as the answer is right, the next problem appears.
Mental math practice at your own pace
Choose your operations
Addition, subtraction, multiplication and whole-number division, on their own or mixed.
Four levels
From easy to expert, the numbers get bigger. No negative answers, except at expert level.
Automatic checking
No Enter key to hunt for: the right answer is recognized as soon as you type it.
Personal record
Your record is saved on your device, so you can track your progress from one session to the next.
Mental math tricks for addition and subtraction
The basic technique is to break numbers apart: 47 + 38 = 47 + 30 + 8 = 77 + 8 = 85. To subtract, you can take away the tens and then the ones (82 − 27 = 82 − 20 − 7 = 55) or count up: from 27 to 30 is 3, from 30 to 82 is 52, so 55. Number bonds to 10 and 100 save a lot of time: 7 + 3, 64 + 36, 100 − 37 = 63. Another habit: round, then adjust. 58 + 99 is 58 + 100 − 1 = 157, and 245 − 98 is 245 − 100 + 2 = 147.
Multiply and divide in your head faster
Multiplying by 5 is the same as multiplying by 10 and halving: 48 × 5 = 480 ÷ 2 = 240. Multiplying by 9 means multiplying by 10 and subtracting the number once: 23 × 9 = 230 − 23 = 207. To multiply a two-digit number by 11, split the digits and put their sum in the middle: 43 × 11 = 4 (4 + 3) 3 = 473; if the sum is more than 9, carry the 1: 68 × 11 = 748. You can also break numbers apart: 7 × 14 = 7 × 10 + 7 × 4 = 98. To divide by 4, halve and halve again: 84 ÷ 4 = 42 ÷ 2 = 21.
How to get better at mental math
A few minutes a day beats one long session a week. Start with a set of 20 problems at easy level and aim for zero mistakes, then move up a level once you answer without hesitating. The 60-second timer then helps you build speed: note your record and try to beat it by one or two answers each time. If one operation slows you down, practice it on its own before mixing it with the others. You need to know your times tables by heart: the "Multiplication Tables" tool lets you review them before tackling the multiplication and division at hard and expert levels. Mental math is practiced throughout elementary school, and these drills work just as well for middle schoolers and adults.
Frequently Asked Questions
How can I get faster at mental math?
Practice a little every day, know your times tables by heart and learn a few tricks: breaking numbers apart, rounding then adjusting, number bonds to 10 and 100. The 60-second challenge lets you track your progress.
What's the trick to multiply by 11 in your head?
For a two-digit number, write its two digits and put their sum in the middle: 52 × 11 = 572. If the sum is more than 9, add the carry to the first digit: 76 × 11 = 836.
How do you multiply by 5 quickly?
Multiply by 10, then divide by 2. For example, 36 × 5 = 360 ÷ 2 = 180.
Do the division problems have remainders?
No, every division problem comes out even: the answer is always a whole number.
Is my record saved?
Yes, your best result is saved on your device, in your browser. It isn't sent anywhere and you don't need an account.