Using the Pigeonhole principle
106791
27 squares of side $1$ inside a circle of radius $2$: Show that three squares share an interior point.
150324
Pigeonhole principle: prove that any set of $n+1$ integers from $\{1,2,...,2n\}$ has two consecutive integers differ by one.
69748
Semi-Ambiguous Combinatorics Problem
111954
Computing the cardinality of a combinatorial set
42744
Prove a number is even using the Pigeonhole Principle
73794
counting with max and min restrictions
41593
Use of Bijection for computation
69827
Set conditions at a permutation
104309
Pigeon-Hole Principle Common Sum
142886
Find set with maximal cardinality given constraints
3663
Finding counterexamples in elementary set theory.
156850
Fix-Point Theorem Proof.
28796
Use the Inclusion-Exclusion Principle to show that for any non-negative integers $m, r, n$ such that $m≤r≤n$...
83222
using trial and error in math problems
39382
Examples of the Pigeonhole Principle
906
Pigeonhole Principle Question - Group of 6 people, do 3 either know each other or not?
23322
Combinatorics Inclusion - Exclusion Principle