binary math

1.
1011= 1+2+0+8=11
101010= 0+2+0+8+0+32=42
11111= 1+2+4+8+16=31
10010= 0+2+0+0+16=18
2.
31-16=15-8=7-4=3-2=1-1=0 31=11111
51-32=19-16=3-2=1-1=0 51=110011
7-4=3-2=1-1=0 7=111
103-64=39-32=7-4=3-2=1-1=0 103=1100111
3.
56 kbs= 3.472 hours
5 megabits/sec= 2.33 minutes
10 megabits/sec= 1.167
4.
25 (and 3/4 of the next mp3)