### Quick description

This page contains links to articles that may be useful for dealing with problems in elementary number theory.

### Techniques in elementary number theory

Modular arithmetic Quick description ( Modular arithmetic is the part of number theory that studies the integers up to multiples of some fixed number. Dealing with integers in this way is typically very useful if one is looking at a question that involves the notion of divisibility. )

## Comments

## I believe Fermat's 'descente

Fri, 01/05/2009 - 17:07 — SameedI believe Fermat's 'descente infinie' deserves a mention here. What's your opinion?

## Definitely agreed. A nice

Fri, 01/05/2009 - 17:24 — gowersDefinitely agreed. A nice example would be the infinite-descent proof that every positive integer is a sum of four squares.

## That's a nice one. Another

Fri, 01/05/2009 - 17:33 — SameedThat's a nice one. Another example might be a proof of the irrationality of or maybe a proof that the diophantine equation has no positive integral solutions.