Doubles and halves
You learn your doubles by heart, and how to use them for near doubles and halves.
How to work it out
- Learn doubles by heart: 6 + 6 = 12.
- If one number is 1 more, double and add 1.
- For halving, find which double gives that number.
7 + 7
- This is a double.
- Double 7 is 14.
- So 7 + 7 = 14.
More examples
6 + 7
- Use the double: 6 + 6 = 12.
- Add one more: 12 + 1 = 13.
- So 6 + 7 = 13.
16 − 8
- Find the double that makes 16: 8 + 8 = 16.
- Half of 16 is 8.
- So 16 − 8 = 8.
7 + 8
- The smaller number is 7.
- Use the double: 7 + 7 = 14.
- Add one more: 14 + 1 = 15.
- Or go to ten first: 7 + 3 = 10.
- Then add the 5: 10 + 5 = 15.
- So 7 + 8 = 15.