hexadecimal

A base 16 numbering system often used in computer programming.

Hexadecimal (base 16)_____Decimal (base 10)

0........................................0
1........................................1
2........................................2
3........................................3
4........................................4
5........................................5
6........................................6
7........................................7
8........................................8
9........................................9
A......................................10
B......................................11
C......................................12
D......................................13
E......................................14
F.......................................15

Q: Why is this important?
A: Ever notice that the thumbwheel on a Wybron ColoRAM II color changer reads 0-F? [Actually, it reads 0-C, so I suppose that makes it Base12, as the RAM PSU can control 24 scroller heads.]

Anyone who deals with MSC or MIDI will get the importance of understanding counting in hex.

Also some lighting consoles will display "FF" instead of "FL" for a channel's intensity at Full. Why? Hex FF = Dec 255, the maximum DMX value.