A drawer contains 10 loose black socks and 10 loose white socks. Without looking, what is the minimum number of socks you must pull out to guarantee you have at least one matching pair?
3 socks
By the Pigeonhole Principle, since there are only 2 possible sock colors, picking 3 socks guarantees at least two of them will match in color.
About this riddle
Math riddles hide a calculation inside a short story. Pull out the numbers, work out what is being asked, and watch for a trick such as a unit change.
Difficulty: Medium. More like this: Math riddles with answers or try Target 24 for a different kind of puzzle.
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