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Double factorial facts for kids

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Double factorial is a method of calculating how many times a number is repeated in a geometric equation. This way, we can calculate the number of times a product is used in its life-time.

The double factorial of n is written as n!!. When n is a positive odd integer, n!! is defined as n \cdot (n-2) \cdot\,  \cdots \, \cdot 3 \cdot 1. When n is an positive even integer, n!! is defined as n \cdot (n-2) \cdot\,  \cdots \, \cdot 4 \cdot 2. By definition, 0!! = 1.

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Kids robot.svg In Spanish: Doble factorial para niños

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Double factorial Facts for Kids. Kiddle Encyclopedia.