Multiplication Tricks You Can Learn Today

Multiplication is the backbone of mental math. These tricks will help you multiply faster without reaching for a calculator.

Multiplying by 11

For single digits, just write the digit twice. 11 × 7 = 77. For two-digit numbers, split the number and put their sum in the middle. 11 × 23: 2_(2+3)_3 = 253. If the sum exceeds 9, carry the 1. 11 × 67: 6_(6+7)_7 = 6_13_7 → 737.

The 9 times table finger trick

Hold up both hands. To multiply 9 × n, fold down the nth finger. The fingers to the left of the folded one represent tens, and those to the right represent ones. For 9 × 6: fold the 6th finger — 5 fingers left (50) and 4 right (4) → 54.

Multiplying by 5

Multiply by 10 and halve the result. 5 × 84 = 840 / 2 = 420. This is often faster than recalling the 5 times table for large numbers.

Squaring numbers ending in 5

For any number ending in 5, the square always ends in 25. The first part is n × (n+1) where n is the remaining digits. 35²: 3 × 4 = 12, so 35² = 1225. 85²: 8 × 9 = 72, so 85² = 7225.

Multiplying by 25

25 = 100/4, so multiply by 100 and divide by 4. 25 × 16 = 1600 / 4 = 400. This is faster than it sounds once you practice it.

The difference of squares trick

To multiply two numbers that are equidistant from a round number: (a+b)(a−b) = a² − b². For 18 × 22: (20−2)(20+2) = 400 − 4 = 396.

Multiplying by 9

Multiply by 10 and subtract the original number. 9 × 34 = 340 − 34 = 306. This works for any number.

Double and halve for even numbers

If one number is even, double one factor and halve the other. 16 × 25: double 25 to get 50, halve 16 to get 8. Now 8 × 50 = 400. Repeat: 4 × 100 = 400.

Want to practice these tricks under time pressure? Try the multiplication practice page or jump into Blitz mode.