SarwaSamadhan

Multiply by 5, 25 and 125 instantly

5, 25 और 125 से तुरंत गुणा

5 = 10/2, 25 = 100/4 and 125 = 1000/8. So multiply by 5, 25 or 125 by adding zeros and halving, quartering or dividing by 8 — usually faster than long multiplication.

5 = 10/2, 25 = 100/4 और 125 = 1000/8। इसलिए शून्य लगाकर 2, 4 या 8 से भाग दें — लंबे गुणा से जल्दी।

The method

Replace the multiplier with a power of ten divided by a small number.

  1. × 5 → add one zero, then divide by 2.
  2. × 25 → add two zeros, then divide by 4.
  3. × 125 → add three zeros, then divide by 8.
Example 46 × 5
460 ÷ 2 = 230
Example 64 × 25
6400 ÷ 4 = 1600
Example 88 × 125
88000 ÷ 8 = 11000

Decimals too

The same works with decimals: 3.6 × 25 = 360 ÷ 4 = 90.

Try it yourself · अभ्यास

  1. 72 × 5
    Show answer

    720 ÷ 2 = 360

  2. 48 × 125
    Show answer

    48000 ÷ 8 = 6000