The 9s Trick

Multiply any number by 9 using your fingers!

1. Hold up both hands with all fingers extended.
2. For 9 × N, count N fingers from the left and fold that finger down.
3. The number of fingers to the left of the folded finger is the tens digit.
4. The number of fingers to the right is the ones digit.

Example: 9 × 7 = 63 (6 fingers left, 3 right)

Multiply by 11

For two-digit numbers:

1. Add the two digits.
2. Put the result between the original digits.

Example: 11 × 25 = 275 (2 + 5 = 7, put 7 between 2 and 5)

Double and Half

When one factor is even, double one and halve the other:

Example: 8 × 7 = (16 × 3.5) = 16 × 3 + 16 ÷ 2 = 48 + 8 = 56