Doubles

Same number twice — worth learning by heart, because they unlock everything else.

The question

What is 4 + 4?

The trick

Doubles are the sums worth knowing without thinking: 1+1=2, 2+2=4, 3+3=6, 4+4=8, 5+5=10. They are also how you work out the ones next to them.

Worked example

1Learn the five doubles as a chant: two, four, six, eight, ten.
2For 4 + 4, that is the fourth one: 8.
3Now the bonus: 4 + 5 is just one more than 4 + 4, so it is 9.

So: 8

Remember it like this

Two hands, two eyes, two ears. Doubles are everywhere on your own body — count them together and the idea sticks.

In the exam

Learn doubles before anything else in addition. They are the foundation almost every other mental addition trick is built on.

Why it works

Doubles have a rhythm, so children memorise them almost effortlessly. Once they are automatic, every 'near double' — 4+5, 6+7 — becomes a single step from something already known.

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

Try it yourself

0/4 correct

1
3 + 3 = ?
3 + 3 = ?
2
5 + 5 = ?
5 + 5 = ?
3
2 + 2 = ?
2 + 2 = ?
4
4 + 5 = ?
4 + 5 = ?