Doubles and Halves
We used the 'five-and-a-bit-ness' of these numbers to help us quickly work out doubles and halves.
In this example we doubled 7 by quickly adding 5 and 5 to make 10. Then adding 2 and 2 to make 4. We then added 10 and 4 together to make 14.
Can you use this technique to quickly work out all the doubles and halves to 20?
5+5=
6+6=
7+7=
8+8=
9+9=
10+10=