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Multiplication Tricks

Multiplying by 5 – Halve, Then Times 10

Multiplying by 5 is really just halving and shifting one place.

This page explains the rule, shows why it works, and walks through worked examples. Then you can try it yourself and check your understanding with practice questions. Use the previous and next links at the bottom to move through the tricks in order.

The rule

The Rule: To multiply by 5 quickly, divide the number by 2 and then multiply by 10.

Why it works

Why It Works: 5 is exactly half of 10. Multiplying by 10 just means sliding every digit one place to the left — something your brain can do instantly — so if you halve the number first and then tack on that shift, you have finished the whole multiplication in two very easy moves instead of one hard one.

Formal Proof (for advanced learners)

5 = 10 ÷ 2, so for any n: n × 5 = n × (10 ÷ 2) = (n ÷ 2) × 10 = (n × 10) ÷ 2. Both orders give the same result, by the associativity and commutativity of multiplication and division.

Examples

  • 36 × 5 → 36 ÷ 2 = 18, then ×10 = 180.
  • 84 × 5 → 84 ÷ 2 = 42, then ×10 = 420.
  • 123 × 5 → 123 ÷ 2 = 61.5, then ×10 = 615.

Step by step

Example A: 356 × 5

  1. Halve 356: 356 ÷ 2 = 178.
  2. Multiply by 10: 178 × 10 = 1780.

Example B: 73 × 5

  1. Halve 73: 73 ÷ 2 = 36.5.
  2. Multiply by 10: 36.5 × 10 = 365.

Try it yourself

Now it is your turn. A new random question appears each time. Type your answer in the box and press Check Answer. If you are right, we show how the trick got you there, step by step. If you are not, you will see the full working two ways, the shortcut and the usual method, so you can spot exactly where your answer differed. Press New Question as often as you like: a few quick rounds is the best way to make the trick feel automatic.

Try It Yourself

Practice questions

Have a go on paper first, then tap Show answer to check your method.

  1. Work out 24 × 5.

    Show answer

    120. Halve 24: 24 ÷ 2 = 12. Multiply by 10: 12 × 10 = 120.

  2. Work out 68 × 5.

    Show answer

    340. Halve 68: 68 ÷ 2 = 34. Multiply by 10: 34 × 10 = 340.

  3. Work out 132 × 5.

    Show answer

    660. Halve 132: 132 ÷ 2 = 66. Multiply by 10: 66 × 10 = 660.

  4. Work out 47 × 5.

    Show answer

    235. Halve 47: 47 ÷ 2 = 23.5. Multiply by 10: 23.5 × 10 = 235.

  5. Stickers come in packs of 5. How many stickers are in 86 packs?

    Show answer

    430. Halve 86: 86 ÷ 2 = 43. Multiply by 10: 43 × 10 = 430.

Tips and watch-outs

  • Odd numbers give a half first: 37 ÷ 2 = 18.5, then 18.5 × 10 = 185.
  • It is the same as multiplying by 10 and then halving. Use whichever order looks easier.