[Monkey Face]

OK...I've got it...I think...

[sionnsar]

Numbering in hexadecimal is a little difficult at first, especially the oddity of seeing letters used as numbers. But it comes with time.

00, 01, 02, ..., 09, 0A, 0B, 0C, 0D, 0E, 0F,
10, 11, 12, ..., 19, 1A, 1B, 1C, 1D, 1E, 1F,
...
90, 91, 92, ..., 99, 9A, 9B, 9C, 9D, 9E, 9F,
A0, A1, A2, ..., A9, AA, AB, AC, AD, AE, AF,
...
F0, F1, F2, ..., F9, FA, FB, FC, FD, FE, FF.

("FD" == 15*[16 -- remember, it's base 16] + 13 = 240 + 13 = 253, or two less than the largest number 255.