Max Characters

[Maddox]

Easier to remember the hex code rather than a number which looks random.

I don't think in hexadecimal, sorry.

[MyndFyre]

What is the max number of characters (letters) that battle.net allowes in a message?

If you're referring to a SID_CHATCOMMAND message, Battle.net truncates when text field is >0xe0 bytes (including null terminator).

Ok, you could have just said 224.

Easier to remember the hex code rather than a number which looks random.

Just like it's easier to remember 1,000 meters in a kilometer than 5280ft in a mile, or 100 degrees at boiling instead of 212 degrees.  

Or 0K as opposed to -273.15^oC or -459.67^oF.

[Spht]

Easier to remember the hex code rather than a number which looks random.

I don't think in hexadecimal, sorry.

Neither do I.  Kp does though.

Some numbers are meant to be read in hex so they're easier to remember, like Botnet's server port 0x5555 (21845).

See Myndfyre's reply for more examples/analogies.