Hi,
that is not a bug, mIRC simply evaluated the incoming string, in this case it evaluated 150 / 2 which is 75
If you want for mIRC to only show exactly what is passed to the alias, then you could do:
alias typed {
set -ln %test $1-
echo -a You typed: %test
}
the -n switch will treat all input as plain text, and not evaluate it.
the -l switch makes the variable local, so don't worry that it's going to be in your variables section, it is deleted when your script finishes.
Greets