# Proof without Words: Squares of Triangular Numbers

by Roger B. Nelsen (Lewis and Clark College)

Mathematics Magazine
June, 1990

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

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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