10 Multiplication Tricks Every Student Should Know
Multiplication does not have to be memorization torture. These ten tricks will help you multiply faster and with less effort. Some work for specific situations, others apply broadly.
1. The 9s Finger Trick
For multiplying 9 by any number 1-10, hold up both hands. Fold down the finger that matches the number you are multiplying by. The fingers to the left are the tens digit, fingers to the right are the ones digit.
Example: 9 × 4
Fold down finger 4. Left: 3 fingers. Right: 6 fingers. Answer: 36
2. Multiply by 10, 100, 1000
Simply add zeros. This is fundamental but worth stating: 45 × 10 = 450, 45 × 100 = 4500, and so on.
3. Multiply by 5
Take the number, divide by 2, then multiply by 10. This works because 5 = 10 ÷ 2.
Example: 48 × 5
48 ÷ 2 = 24, then 24 × 10 = 240
4. Multiply by 11 (Two-Digit Numbers)
Add the two digits and place the sum between them. If the sum is greater than 9, carry the 1.
Example: 63 × 11
6 + 3 = 9. Place 9 between 6 and 3. Answer: 693
Example: 78 × 11
7 + 8 = 15. Put 5 in middle, carry 1. Answer: 858
5. Squaring Numbers Ending in 5
Multiply the first digit by itself plus one, then add 25.
Example: 75²
7 × 8 = 56. Add 25. Answer: 5625
6. Multiply by 4
Double the number twice. Doubling is easier than multiplying by 4 directly.
Example: 27 × 4
27 × 2 = 54, then 54 × 2 = 108
7. Multiply by 9 (Alternative Method)
Multiply by 10, then subtract the original number.
Example: 23 × 9
23 × 10 = 230, then 230 - 23 = 207
8. Multiply Numbers Close to 100
Find how far each number is from 100. Cross-subtract, then add the product of the differences.
Example: 97 × 96
97 is 3 below 100, 96 is 4 below. Cross-subtract: 97 - 4 = 93. Multiply differences: 3 × 4 = 12. Answer: 9312
9. Double and Halve
If one number is hard to work with, double one and halve the other. The product stays the same.
Example: 35 × 16
Double 35 to 70, halve 16 to 8. Now calculate 70 × 8 = 560
10. Break Apart Numbers
Use distributive property to break numbers into easier pieces.
Example: 23 × 7
(20 × 7) + (3 × 7) = 140 + 21 = 161
Practice Is Key
These tricks only help if you can recall them quickly. Practice each one until it becomes automatic. Start by focusing on one or two that apply to your current math work, then add more as they become natural.
Put Your Skills to the Test
Numbo Math puzzles will challenge you to use these tricks under time pressure.
Play Numbo Math