In English we use the word combination loosely, without thinking if the order of things is important. In other words:

Find out how many different ways to choose items. For an in-depth explanation of the formulas please visit Combinations and Permutations.

Combinations and Permutations. Combinations and Permutations Calculator.

Math explained in easy language, plus puzzles, games, quizzes, worksheets and a forum. For K-12 kids, teachers and parents.

You can read a gentle introduction to Sequences in Common Number Patterns. A Sequence is a list of things (usually numbers) that are in order.

A binomial is a polynomial with two terms. What happens when we multiply a binomial by itself ... many times? a+b is a binomial (the two terms...

Math explained in easy language, plus puzzles, games, quizzes, worksheets and a forum. For K-12 kids, teachers and parents.

Energy is the capacity to do work. The unit of energy is J (Joule) which is also kg m2/s2 (kilogram meter squared per second squared).

(There is another Eulers Formula about Geometry,this page is about the one used in Complex Numbers) ... First, you may have seen the famous Eulers Identity

The factorial function (symbol: !) says to multiply all whole numbers from our chosen number down to 1. Examples: