New posts in pigeonhole-principle

Pigeonhole principle: Coloring $11$ points of a $5\times 5$ square grid

Pigeonhole Principle: Among any seven integers, there must be two whose sum or difference is divisible by $10$

Nonconstant polynomials have a composite value in a UFD with finitely many units

Combi Problem - Proving Existence of a row

Russia (2000) contest:Prove the existence of a pair of rows and columns with intersections differently coloured

Some three consecutive numbers sum to at least $32$

Showing there is a node in the graph with only one edge

Given 7 arbitrary integers,sum of 4 of them is divisible by 4

Elementary number theory in sets

Prove that $ax^2 + by^2 \equiv c \pmod{p}$ has integer solutions

Pigeonhole Principle Question: Given any 5 points inside a square of side length 2, there is always a pair whose distance apart is at most $\sqrt2$

Showing there is a node in the graph with one and only one edge

Proof that Fibonacci Sequence modulo m is periodic? [duplicate]

Show that given seven real numbers, it is always possible take two of them, such that $\left\vert\frac{a-b}{1+ab}\right\vert<\frac{1}{\sqrt{3}}$

The pigeonhole principle - how to solve questions like that?

Jessica the Combinatorics Student, part 2

Prove a subset from 1000 points contains one point that is strictly larger than the other one

Combinatorics problem (Pigeonhole principle).

A Pigeonhole-Principle from IMO Shortlist.

Proving that among any $2n - 1$ integers, there's always a subset of $n$ which sum to a multiple of $n$