Binary code is both intresting and confusing. Here is how the number part of it works:
English
Binary
0
0
1
01
2
10
3
11
4
100
5
101
6
110
7
111
8
1000
9
1001
10
1010
11
1011
12
1100
13
1101
14
1110
15
1111
And so on...