## irrational number

We take the real numbers for granted, but what are they really?

Here's one of the most elegant proofs in all of maths. Rejoice in its simplicity!

**Chris Sangwin**takes us through excerpts of Euler's algebra text book and finds that modern teaching could have something to learn from Euler's methods.

Nineteenth-century German mathematician Leopold Kronecker once said

God created the integers, all the rest is the work of man.

**Jon Walthoe**explains the tricks involved and how great thinkers like Pythagoras, Newton and Gödel tackled the problems.