This math skill teaches how to simplify and evaluate a division of factorials by cancelling common terms in the numerator and denominator. Factorials represent a sequence of products counting down from a number, which are simplified and calculated for division.
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Meaning and value of a factorial division
Test your understanding of meaning of a factorial division by practicing it! Work through the below exercises to use it in practice.
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What is the meaning and value of this factorial division? When we see a number with the exclamation point beside it, it is called a factorial, and is used a lot in probability.
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Quite simply, 5 factorial means 5 multiplied in sequence by every smaller number, so 5 times 4 times 3 times 2. 3 factorial is 3 times 2. We can ignore multiplying by 1 because that doesn't change the value.
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Now if we cancel like terms on top and bottom, we are left with just 5 times 4
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Multiplying it out, we get 20, so 5 factorial, over 3 factorial, is equal to 20