Simple Math- Subtraction

Front 1

1-1

Back 1

0

Front 2

1
- 1

Back 2

0

Front 3

2-1

Back 3

1

Front 4

2
- 1

Back 4

1

Front 5

3-1

Back 5

2

Front 6

3
- 1

Back 6

2

Front 7

4-1

Back 7

3

Front 8

4
- 1

Back 8

3

Front 9

5-1

Back 9

4

Front 10

5
- 1

Back 10

4

Front 11

6-1

Back 11

5

Front 12

6
- 1

Back 12

5

Front 13

7-1

Back 13

6

Front 14

7
- 1

Back 14

6

Front 15

8-1

Back 15

7

Front 16

8
- 1

Back 16

7

Front 17

9-1

Back 17

8

Front 18

9
- 1

Back 18

8