Hexadecimal

Uses: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F

In hexadecimal, every location is 2^n in decimal. 0-F allows us to represent 0 through 15 in decimal with a single “digit”.

9 in hexadecimal would be:

16^n16^216^116^0=1
9

10 in hexadecimal would be:

16^n16^216^116^0=1
A

15 in hexadecimal would be:

16^n16^216^116^0=1
F

16 in hexadecimal would be:

16^n16^216^116^0=1
10

Since F is the highest you can count, the highest you could count with two digits would be FF, or 16*F + 1*F = 250 + 15 = 255.