A Factorials Guide [Math, Algebra]

Hello. This short post is on factorials. (Prerequisites: Multiplication, Division and Fractions)

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To start, here are a few examples of factorials.

QuickLaTeX Source

As you can see, a factorial is a nice and compact way of expressing the multiplication of descending positive whole numbers (n = 1, 2, 3, ...). The exclamation mark does not mean that the number is screaming or yelling at you.

With factorials, the general case is:

QuickLaTeX Source

An alternative version of factorials is in ascending order:

QuickLaTeX Source

Special factorial cases include 1! = 1 and 0! = 1.

Division With Factorials

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You may encounter fractions with factorials in the numerator and in the denominator. Here are some examples.

Example One

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Example Two

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Example Three

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Practice Problems

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I have these practice problems all in one image file (Credit to QuickLaTeX.com).

QuickLaTeX Source

Solutions

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1. 2400

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3. 2.5

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