Multiply by 2 to 4

Front

2 x 0

Back

0

Front

2 x 1

Back

2

Front

2 x 2

Back

4

Front

2 x 3

Back

6

Front

2 x 4

Back

8

Front

2 x 5

Back

10

Front

2 x 6

Back

12

Front

2 x 7

Back

14

Front

2 x 8

Back

16

Front

2 x 9

Back

18