Addition
1+1=
2
1-1
0
What number comes before 2
1
What number comes after 3
4
1x1=
1
1+0=
1
2-1=
1
What number comes before 4
3
What number comes after 4
5
2x1
2
2+1=
3
3-2=
1
What number comes before 5
4
What number comes after 6
7
3x2
6
3+2=
5
4-2=
2
What number comes before 6
5
What number comes after 8
9
4x2
8
2+2=
4
5-3=
2
What number comes before 9
8
What number comes after 20
21
5x2
10