Doubling and Halving
An early-years lesson on doubling and halving: double to make twice as much, halve to share fairly in two, with worked examples, a table and a quiz.
Key takeaways
- Doubling a number means adding it to itself, or making two equal groups of it.
- Halving a number means splitting it fairly into two equal groups.
- Doubling and halving are opposites: double 4 is 8, and half of 8 is 4.
- You can only halve a number evenly if it is an even number.
Two of the same: doubling and halving
Two everyday ideas live at the heart of this lesson. Doubling means making twice as much. Halving means splitting something fairly in two. You already do both without thinking — when you share a chocolate bar with a friend (halving) or ask for double sprinkles on your ice cream (doubling). This lesson shows you the maths hiding inside those moments.
The best part: doubling and halving are opposites. One builds up, the other breaks down. Once you see how they undo each other, both become easy.
What is doubling?
To double a number, you add it to itself. You make two equal groups and put them together.
- Double 2 is 2 + 2 = 4.
- Double 3 is 3 + 3 = 6.
- Double 5 is 5 + 5 = 10.
Think of a butterfly. One wing has 3 spots, so both wings together have double 3 = 6 spots. Doubling shows up anywhere things come in matching pairs: two hands, two socks, two wings.
What is halving?
To halve a number, you split it fairly into two equal groups. Each group gets the same amount — that is what "fair" means.
- Half of 4 is 2 (because 2 + 2 = 4).
- Half of 6 is 3 (because 3 + 3 = 6).
- Half of 10 is 5 (because 5 + 5 = 10).
Picture sharing 8 grapes between you and a friend. You give one to them, one to you, and keep going. You each end up with 4. Half of 8 is 4.
Doubles and halves go together
Look closely and you will spot the magic. Doubling and halving are a perfect pair:
| Number | Double it | Half of the double |
|---|---|---|
| 2 | 4 | 2 |
| 3 | 6 | 3 |
| 4 | 8 | 4 |
| 5 | 10 | 5 |
See how the last column matches the first? Halving undoes doubling. If you double a number and then halve it, you return to where you started. This is the why: they are two sides of the same idea, just travelling in opposite directions.
Why some numbers won't halve evenly
You can only halve a number into two equal whole groups if it is an even number. Even numbers (2, 4, 6, 8, 10) split perfectly. Odd numbers (3, 5, 7, 9) always leave one extra — one side would get more than the other, which is not fair. To learn which numbers are even and which are odd, see our lesson on odd and even numbers.
This is also why every doubled number is even: when you add a number to itself, the two equal groups can always be shared back evenly.
Worked example 1: doubling
What is double 7?
Double means add the number to itself: 7 + 7. Count on from 7: 8, 9, 10, 11, 12, 13, 14. So double 7 = 14. (And because doubling makes even numbers, the answer 14 is even.)
Worked example 2: halving
What is half of 12?
Split 12 into two equal groups. Deal them out one at a time: 1 and 1, 2 and 2, all the way to 6 and 6. Each group has 6. So half of 12 = 6.
Worked example 3: doubling near a ten
What is double 8?
8 + 8. A handy trick: double 8 is the same as 8 + 8 = 16. You can check it with the two times table, since doubling is just multiplying by 2. This link is why doubling is such a strong first step towards times tables.
Why doubling and halving matter
These two skills are everywhere. Doubling is the doorway to the two times table and to multiplication: double a number is the same as "times two". Halving is the doorway to dividing by two and to sharing fairly, which you do every time you split something with a friend. Strong doublers and halvers do mental maths quickly, because many sums become easy once you spot a double or a half hiding inside.
Try it yourself
- Double the dots. Draw a number of dots, then draw the same number again next to it. Count them all — that is the double!
- Fair share. Take 10 small toys. Share them fairly between two cups. How many in each? That is half of 10.
- Odd one out. Try to halve 7 toys into two cups. What happens? (One cup gets one extra — 7 is odd.)
- There and back. Pick a number, double it, then halve your answer. Did you land back on your starting number? You will every time.
Practise a few doubles and halves each day, and they will pop into your head in a flash.
Quick quiz
Test yourself and earn XP
What is double 5?
Double 5 means 5 + 5, which is 10.
What is half of 8?
Half of 8 splits 8 into two equal groups of 4, so the answer is 4.
Doubling is the opposite of which?
Doubling and halving undo each other. Double 6 is 12, and half of 12 is 6.
Which number cannot be halved into two equal whole groups?
7 is an odd number, so it cannot be split into two equal whole groups — one side would have more.
You double 3, then halve the answer. What number do you end with?
Double 3 is 6, and half of 6 is 3. Halving undoes the doubling, so you are back to 3.
FAQ
Doubling means making twice as much. You add the number to itself, so double 4 is 4 + 4 = 8. It is the same as making two equal groups.
Only even numbers split into two equal whole groups. Odd numbers like 7 leave one extra, so you cannot share them perfectly in two without using a half.
Doubling is the start of the two times table and multiplication, while halving is the start of dividing by two and sharing fairly. Both build number confidence.
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