15 Fun Maths Tricks Every Student Should Know
Maths becomes fun the moment you can do it fast. These 15 tricks turn slow calculations into quick mental wins — perfect for school, exams and impressing your friends. Try each one with your own numbers as you read.
Quick multiplication tricks
- Multiply by 11: For a 2-digit number, add the two digits and put the sum in the middle. 35 × 11 → 3_(3+5)_5 → 385.
- Multiply by 5: Halve the number, then multiply by 10. 48 × 5 → 24 × 10 = 240.
- Multiply by 9: Multiply by 10 and subtract the number. 7 × 9 → 70 − 7 = 63.
- Multiply by 25: Divide by 4 and add two zeros. 16 × 25 → 4 → 400.
Instant squares
- Square of numbers ending in 5: Take the first digit(s), multiply by the next number, then attach 25. 65² → 6 × 7 = 42 → 4225.
- Square near 100: For 98², subtract (100 − 98) from 98 → 96, then append the square of the difference (2² = 04) → 9604.
Divisibility shortcuts
- Divisible by 3: if the digit sum is divisible by 3 (e.g. 123 → 1+2+3 = 6 ✔).
- Divisible by 4: if the last two digits form a number divisible by 4.
- Divisible by 9: if the digit sum is divisible by 9.
- Divisible by 11: if the alternating digit sum is 0 or a multiple of 11.
Handy everyday tricks
- Percentages flip: x% of y = y% of x. 18% of 50 = 50% of 18 = 9.
- Quick average: for evenly spaced numbers, the average is (first + last) ÷ 2.
- Adding from left to right is faster mentally than the right-to-left method taught in school.
- Subtract from 1000: subtract each digit from 9, and the last from 10. 1000 − 467 → 533.
- The 9 times table on your fingers: fold the finger for the multiplier; fingers left and right give tens and units.
- Round and adjust: 99 × 7 → 100 × 7 − 7 = 693.
How to get faster with these
Tricks only stick with practice. Try two or three a day on real numbers, and they soon become automatic — saving precious minutes in exams. For students who love speed maths, our Vedic maths guide goes further, and our Class 9 and Class 10 maths tuition builds these habits into everyday problem-solving.
Frequently asked questions
Do maths tricks help in exams?
Yes. Mental-maths tricks speed up calculations and reduce silly errors, freeing time for harder questions. They work best when practised until they feel automatic.
Which maths trick is best for fast multiplication?
The "multiply by 11" and "numbers ending in 5" tricks give instant results. For general speed, learning to multiply from left to right and rounding-and-adjusting helps the most.
At what age can students learn these tricks?
Most tricks suit students from Class 5 upwards, once multiplication tables are comfortable. Younger learners can start with the by-5, by-9 and finger tricks.