Question

Pigeon hole principle and it's use?

Answer 1

In mathematics, the pigeonhole principle states that if n items are put into m containers, with n > m, then at least one container must contain more than one item. This theorem is exemplified in real life by truisms like "in any group of three gloves there must be at least two left gloves or two right gloves".
The first use of the pigeonhole principle is said to be by Dirichlet in 1834, and for this reason it is also known as the Dirichlet principle.