Buttons odd and even

6 is even.

We can write 3+3=6 to show this.

7 is odd.

We can write 3+3+1=7 to show this.
Count out 20 buttons.
- Take 8 buttons and count them by twos to determine if there is an even or odd amount. Write an equation showing if it is even or odd.
- Take 13 buttons and count them by twos to determine if there is an even or odd amount. Write an equation showing if it is even or odd.
- Take 18 buttons and count them by twos to determine if there is an even or odd amount. Write an equation showing if it is even or odd.