The Near Doubles Strategy

What is a near double?

A double is a number added to itself, like 6 + 6 or 8 + 8. A near double is an addition where the two numbers are almost the same — only one or two apart. Sums like 6 + 7, 8 + 9 and 5 + 7 are all near doubles.

The clever idea is this: you do not work a near double out from scratch. Instead you lean on a double you already know, then make a small adjustment.

Why the trick works

Look at 6 + 7. The 7 is just one more than 6. So 6 + 7 must be one more than 6 + 6.

• 6 + 6 = 12 (a double you know)
• 6 + 7 is one more, so 12 + 1 = 13

That is the whole strategy: double, then adjust. It works because adding 1 to one of the numbers adds exactly 1 to the total. Knowing why means you will never mix up whether to add or take away — you simply check if your near double is bigger or smaller than the double.

If you would like to strengthen the doubles themselves first, our lesson on doubling and halving is a great place to start.

The two kinds of near double

There are two ways to use a double, and both give the same answer.

Sum	Double to use	Adjust	Answer
6 + 7	double 6 = 12	+ 1	13
6 + 7	double 7 = 14	− 1	13
8 + 9	double 8 = 16	+ 1	17
5 + 7	double 6 = 12	(5+7 = 12)	12
10 + 12	double 10 = 20	+ 2	22

Notice the row for 5 + 7. The two numbers are two apart, with 6 sitting exactly between them. In that case the answer is simply double the middle number — 5 + 7 = double 6 = 12. Neat!

Worked example 1: one apart

Work out 8 + 9.

1. Pick the double you know: 8 + 8 = 16.
2. The 9 is one more than 8, so add 1.
3. 16 + 1 = 17.

So 8 + 9 = 17.

Worked example 2: using the bigger double

Work out 6 + 7 the other way.

1. Use 7 + 7 = 14.
2. The 6 is one less than 7, so take 1 away.
3. 14 − 1 = 13.

Same answer, 13 — you can choose whichever double feels easier.

Worked example 3: two apart

Work out 5 + 7.

The numbers are two apart, and 6 is in the middle. So:

• Double the middle number: 6 + 6 = 12.
• 5 + 7 = 12.

Why this strategy matters

Doubles are some of the easiest facts to remember — many children know them as quickly as a song. The near doubles strategy lets you stretch that small set of easy facts to cover lots of trickier sums. Instead of counting on your fingers, you recall one double and make a tiny adjustment, which is faster and far less likely to go wrong.

Try it yourself

You will need a set of number cards 1 to 10 (or you can write them on paper).

1. Shuffle the cards and turn over two of them.
2. If the numbers are one or two apart, it is a near double — solve it using a double.
3. Say your method out loud: "Double 6 is 12, plus 1 is 13."
4. Keep a tally of how many near doubles you spot in 10 turns.
5. Challenge: Race a partner. Whoever says the correct answer first wins the card.

What's next?

Near doubles is one of many quick tricks. Build your toolkit with our lesson on mental math strategies, then practise putting them together in addition and subtraction.