# Proof without Words: Squares of Triangular Numbers

by Roger B. Nelsen (Lewis and Clark College)

Mathematics Magazine
June, 1990

Subject classification(s): Geometric Proof | Geometry and Topology | Number Patterns | Patterns and Sequences | Numbers and Computation
Applicable Course(s): 4.10 Math for High School Teachers | 4.1 Introduction to Proofs | 3.7 Discrete Math

The author proves visually that the square of the $$n$$th triangular number equals the sum of the cubes of the first $$n$$ positive integers.

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