20
Adding binary numbers
   1 0 1 0
   0 1 1 1
1 0 0 0 1
1 x 2 3 + 0 x 2 2 + 1 x 2 1 + 0 x 2 0  = 10
0 x 2 3 + 1 x 2 2 + 1 x 2 1 + 1 x 2 0  = 7