Pascal's Triangle

To build the triangle, start with "1" at the top, then continue placing numbers below it in a triangular pattern. 

Each number is the two numbers above it added together (except for the edges, which are all "1").

A Formula for Any Entry in The Triangle

In fact there is a formula from Combinations for working out the value at any place in Pascal's triangle:

It is commonly called "n choose k" and written like this:

Notation: "n choose k" can also be written C(n,k), ⁿC_k or even _nC_k.

 So Pascal's Triangle could also be an "n choose k" triangle like this

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