Multiply by 4s

Front

4 x 1

Back

4

Front

4 x 0

Back

0

Front

4 x 2

Back

8

Front

4 x 3

Back

12

Front

4 x 4

Back

16

Front

4 x 5

Back

20

Front

2 x 4

Back

8

Front

1 x 4

Back

4

Front

4 x 6

Back

24

Front

4 x 8

Back

32