Triangular Numbers: Sum from 1 to N
November 2, 2011
Kitten and I covered triangular numbers a couple months ago in our Competition Math for Middle School book, but I think it’s time to revisit the topic. I like the method James Tanton gives in this new video:
How Do You Count Infinity?
Tanton continues to play with triangular numbers in the next video, which is probably too abstract for Kitten, but I enjoyed it. The triangular numbers are countably infinite, as are the square numbers. But if you look at it another way…
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Have more fun on Let’s Play Math! blog:
- Puzzle: Figuring Out Figurate Numbers
- Visual Proof of the Pythagorean Theorem
- Euclid’s Geometric Algebra
- Math Club: Counting 101
- Sign Up for the MathCounts Club Program
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Thanks for these videos! I’m always looking for ways to make math fun and interesting.