Fast Multiplication Tricks
Reliable shortcuts for common multiplication patterns.
Multiply by 568 × 5 = 340
68 × 10 = 680
680 ÷ 2 = 340
680 ÷ 2 = 340
Why: 5 = 10 ÷ 2.
Multiply by 947 × 9 = 423
47 × 10 = 470
470 − 47 = 423
470 − 47 = 423
Why: 9 = 10 − 1.
Multiply by 1136 × 11 = 396
36 × 10 = 360
360 + 36 = 396
360 + 36 = 396
Why: 11 = 10 + 1.
Multiply by 2548 × 25 = 1,200
48 × 100 = 4,800
4,800 ÷ 4 = 1,200
4,800 ÷ 4 = 1,200
Why: 25 = 100 ÷ 4.
Multiply by 5034 × 50 = 1,700
34 × 100 = 3,400
3,400 ÷ 2 = 1,700
3,400 ÷ 2 = 1,700
Why: 50 = 100 ÷ 2.
Multiply by 9972 × 99 = 7,128
72 × 100 = 7,200
7,200 − 72 = 7,128
7,200 − 72 = 7,128
Why: 99 = 100 − 1.
Double and halve16 × 35 = 560
8 × 70 = 560
or 4 × 140 = 560
or 4 × 140 = 560
Why: Halving one factor and doubling the other leaves the product unchanged.