Test Your Knowledge Tuesday!

The answer to last week's tester: the letter T would be next because there are no curves in it

This week challenge:
Your sock drawer contains ten pairs of white socks and ten pairs of black socks. If you're only allowed to take one sock from the drawer at a time and you can't see what color sock you're taking until you've taken it, how many socks do you have to take before you're guaranteed to have at least one matching pair?

Feel free to post answers in the comments section, or return next Tuesday to find out what the answer is.

Your time...starts...NOW!