# Combinations: Picking K out of N

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Baskin Robbins serves "31 Flavors" of ice cream. How many different two-scoop ice cream cones are possible if two different flavors are used on each cone and the order of the scoops doesn't matter?* (* Means chocolate on top and vanilla on the bottom is the same as chocolate on the bottom and vanilla on top.)

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#### Solution Preview

Hello and thank you for posting your question to Brainmass.

This is a "pick k out of n" problem.

with no order, it is:

C(k,n)=n!/[k!*(n-k)!]

Where n! is n factorial:

n! = ...

#### Solution Summary

The solution shows how to reach the answer first by simple plug-n-chug and then explains how to do it using simple principles.

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