See 9 - Think 10!

We have been learning to make tidy numbers to help us solve addition problems.

Tidy numbers make it easy to add.

10, 40, 50, 80, 100, 300, 700 and 1000 are some of the tidy numbers that we know.

We notice that they all end with a '0'.

We know that to make a number that ends with a 9 in to a tidy number, we need to add 1 more.
We know that we can make numbers that end with 8 in to a tidy number by adding on 2 more.

Here are some examples:

39 add 1 is 40
89 add one is 90
79 plus 1 is 80
49 + 1 = 50