I think most of us have run into the predecessor joke here already:

**There are 10 kinds of people: those who understand binary notation, and those who don’t.**

I ran across two variants that amused me enough to want to share them:

**There are 10 kinds of people: those who understand ternary notation, those who don’t, and those who thought this was going to be the binary joke.**

And…

**There are 10 kinds of people, 1 group who understand hexadecimal notation, and F the rest.**

Along with all this is:

**Christmas is Hallowe’en.** Proof: 25 DEC = 31 OCT