I would like the choices: ”strict national” ”generous” with option “accept expressions”

Strict: 3,000.50 (US) or 3.000,50 (Sweden); etc

Generous: all strict variants plus “3 000.50” or “3 000,50” (I’d like to add 3,0005E+3 3,0005*10^3 even 3000½)

Expressions: 3E3+12/2

I’ve used a numerical tutorial quiz written in PERL to which I added a reg expression filter to process the input string before evaluating it numerically. I’m not sure what numerical formats PHP uses natively but for perl I used:

, becomes . (this would make problems with thousands separators unless it checked first for both) ^ becomes ** E becomes 10* and even ½ becomes .5 (though it would be good to warn students that it’s not a good idea to use ½.)

Another possibility would be to have a filtering choice in the individual question before processing the answer string which could have simple: make [,] become [.] or maybe even som reg exp possibility.

It would be good to have a JavaScript warning when users try to use characters that will make problems (not be understood).