This principle can be useful to prove apparently difficult problems. For example, this principle can easily prove that at least two people in [[New Jersey]] must have precisely the same number of hairs on their head. This is because there are more people living in [[New Jersey]] than possible numbers of hairs on one's head. | This principle can be useful to prove apparently difficult problems. For example, this principle can easily prove that at least two people in [[New Jersey]] must have precisely the same number of hairs on their head. This is because there are more people living in [[New Jersey]] than possible numbers of hairs on one's head. |