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Proof Without Words: Every Octagonal Number Is the Difference of Two Squares

by Elizabeth Jakubowski (Florida State University) and Hasan Unal (Yildiz Technical University Turkey)

This article originally appeared in:
Mathematics Magazine
June, 2009

Subject classification(s): Algebra and Number Theory | Number Theory
Applicable Course(s): 4.3 Number Theory

This paper offers a visual illustration of the fact that every octagonal number is the difference of two squares.

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Capsule Course Topic(s):
Number Theory | Numbers With Special Forms or Properties
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