Ten red socks and ten blue socks are all mixed up in a dresser drawer. The 20 socks are exactly alike except for their colour. The room is in pitch darkness and you want two matching socks. What is the smallest number of socks you must take out of the drawer in order to be certain that you have a pair that match?
The answer is just 3. You’ll end up with either:
- 3 blue socks
- 2 blue socks & 1 red sock
- 2 red socks & 1 blue sock
- 3 red socks
…and that would give you a usable pair every time.