The 9s Finger Multiplication Trick

Problem

The 9 times table is one of the hardest to memorize, especially for students and anyone doing quick mental math.

Solution

Hold up 10 fingers. To multiply 9 × N, fold down finger #N. Fingers to the left = tens digit, fingers to the right = ones digit.

Benefit

Never memorize the 9 times table again — works for 9×1 through 9×10 with 100% accuracy using your hands.

Example

9 × 4: fold finger #4
→ 3 fingers left | 6 fingers right = 36 ✓

9 × 7: fold finger #7
→ 6 fingers left | 3 fingers right = 63 ✓

9 × 3: fold finger #3
→ 2 fingers left | 7 fingers right = 27 ✓

9 × 9: fold finger #9
→ 8 fingers left | 1 finger right = 81 ✓

Bonus: digits of any 9× answer always sum to 9!