The visual clue for the relationship between the sum of natural numbers and the sum of the product of two consecutive integers is presented. This relationship indicates the reason why the sum of integers, 1 + 2 + ... + n, is represented by a factor of (n + 1)n.

sum of natural numbers, sum of the product of two consecutive numbers, proof without words, visual thinking.

Received: October 11, 2021; Accepted: December 3, 2021; Published: February 22, 2022

How to cite this article: Yukio Kobayashi, Proof without words: relationship between the sum of natural numbers and the sum of the product of two consecutive integers, Far East Journal of Mathematical Education 22 (2022), 1-3. http://dx.doi.org/10.17654/0973563122001

This Open Access Article is Licensed under Creative Commons Attribution 4.0 International License

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