1024
24 = 16
There are 16 decimal numbers that can be represented by 4-bits.
6 bits
8 bits = 64 character
4
A total of 65,536 items can be represented with 16 bits. A total of 64 items can be represented with 6 bits and 1024 items with 64 bits.
1000
2
2 power n
2^12=4096
23 can be represented in binary as 10111 and would therefore require 5 bits to represent.
256 in total - including zero.