Pigeonhole Principle, Discrete Mathematics, Combinatorics, Mathematical Logic, Problem Solving.
So the 5 cards we’ve picked must belong to these 4 suits. By the pigeonhole principle, 2 or more must belong to the same suit. Socks problem: If we have 10 black socks and 10 white socks, picking up just 3 socks guarantees us a pair. Imagine there are two holes, each containing socks of a single