## Arithmetic

Posted September 1st, 2007 by Isoscel

Arithmetic pages:

Learn how to calculate fast

Multiply with 11 fast

The square of a number that ends in 5

Irrational numbers

A Proof that the Square Root of 2 is Irational

Special numbers in Arithmetic

142857

Fibonacci number

Divisibility tests

Test if a number is divisible by 3

Test if a number is divisible by 6

Test if a number is divisible by 9

Test if a number is divisible by a power of 2

Prime numbers

The definition of prime numbers

There are an infinite number of prime numbers

Calculate sums

The sum of the first n natural numbers

The sum of the first n odd natural numbers

The sum of the squares of the first n natural numbers

The sum of the squares of the first n odd natural numbers

The sum of the cubes of the first n natural numbers