# List by Author: Yutaka Nishiyama

Some lovely proofs by picture

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 61746174 is a very mysterious number. Yutaka Nishiyama explains why, and how beautiful mathematical oddities can inspire us to discover new mathematics.
A bright ideaWhat do computers and light switches have in common? Yutaka Nishiyama illuminates the connection between light bulbs, logic and binary arithmetic.
• Want facts and want them fast? Our Maths in a minute series explores key mathematical concepts in just a few words.