Hide solutions to answered problems?

[phyisis]

If I want to show a problem to someone (in person)- and I've already solved it, I'd rather not spoil the answer for them. I know I can just log out, or take a screenshot, or retype the problems, but a checkbox or collapsible box to hide the answer would be nice.

[hk]

you could use projecteuler.info .This site also contains the projecteuler problems.