Multiply by 5

Halve the number, then add a zero.

The question

What is 48 × 5?

The trick

Cut the number in half, then multiply by 10 by adding a zero.

Worked example

1Half of 48 is 24
2Add a zero: 240

So: 240

Remember it like this

Five is half of ten. So halve it, then ten it.

In the exam

When the number is odd the half ends in .5, and the zero turns it into a 5. 37 × 5 → half is 18.5 → 185. Write the half down before adding the zero; doing both steps at once is where slips happen.

Why it works

5 is just 10 ÷ 2. So multiplying by 5 is the same as halving and then multiplying by 10 — and multiplying by 10 is free.

Explain this to my childGet the words to teach it, in your language

Try it yourself

0/4 correct

1
86 × 5
86 × 5
2
124 × 5
124 × 5
3
37 × 5
37 × 5
4
246 × 5
246 × 5