[robertAngst]

I teach a programming class and one of the 'easy' things I ask about is- "Have you taken algebra?"

All but 1 person had taken algebra, and with that I start into variables and functions.

So yes, people learn competent math skills in high school.

[Kaveren]

Knowing what functions and variables are is below high school level, and I'd say it'd be comparative to knowing basic greetings in a foreign language. I doubt that many students who don't go on to study math after high school remember what's taught in courses at or past the Algebra 2 level.