Question

What is the pigeonhole principle?

Answer 1

Pigeonhole principle:

Pigeonhole principle roughly states that if there are few boxes available also, there are few objects that are greater than the total number of boxes as well as one needs to place objects in the given boxes, then at least one box must contain more than one such objects.

Hence, pigeonhole principle states that if more than $n$ pigeons are placed into $n$ pigeonholes, some pigeonholes must contain more than one pigeon.