List by Author: Yutaka Nishiyama

Some lovely proofs by picture
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Don't like trigonometry? Don't worry, here are three beautiful proofs of a well-known result that make do without it.
Circles rolling on circles

Imagine a circle with radius 1 cm rolling completely along the circumference of a circle with radius 4 cm. How many rotations did the smaller circle make? Be prepared for a surprise!
Having fun with unit fractions

The number 1 can be written as a sum of unit fractions, that is fractions with 1 in the numerator. But how long can we make such a sum?
Mysterious number 6174
6174 is a very mysterious number. Yutaka Nishiyama explains why, and how beautiful mathematical oddities can inspire us to discover new mathematics.
A bright idea
What do computers and light switches have in common? Yutaka Nishiyama illuminates the connection between light bulbs, logic and binary arithmetic.