# Counting, permutations, and combinations

This course is a part of
**Statistics and probability**, a 16-course Topic series from Khan Academy.

This unit covers methods for counting how many possible outcomes there are in various situations. We'll learn about factorial, permutations, and combinations. We'll also look at how to use these ideas to find probabilities.

This course contains 4 segments:

**Counting principle and factorial**

The counting principal tells us that we can multiply the number of choices together to get a count of the total possible outcomes. If you own two pairs of pants and three shirts, then you have six possible outfits.

**Permutations**

Permutations count how many ways you can select and arrange items or people from a larger group. For example, how many different ways can we award a gold, silver, and bronze medal to three runners out of a group of 10?

**Combinations**

Combinations are similar to permutations. Combinations count how many ways we can pick a group of people or things from a larger group where order doesn't matter. For example, how many different groups of 3 people can a company with 10 employees send on a business trip?

**Combinatorics and probability**

Once we understand the counting principle, permutations, and combinations, we can use those concepts to calculate some pretty advanced probabilities!

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Rating | Not enough ratings |
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Length | 4 segments |

Starts | On Demand (Start anytime) |

Cost | Free |

From | Khan Academy |

Download Videos | On all desktop and mobile devices |

Language | English |

Subjects | Mathematics Data Science |

Tags | Math Statistics and probability |

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Rating | Not enough ratings |
---|---|

Length | 4 segments |

Starts | On Demand (Start anytime) |

Cost | Free |

From | Khan Academy |

Download Videos | On all desktop and mobile devices |

Language | English |

Subjects | Mathematics Data Science |

Tags | Math Statistics and probability |

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