# Author: Yutaka Nishiyama

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! |
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? |

6174 is a very mysterious number.
Yutaka Nishiyama explains why, and how beautiful mathematical oddities can inspire us to discover new mathematics. |
What do computers and light switches have in common?
Yutaka Nishiyama illuminates the connection between light bulbs, logic and binary arithmetic. |