# Double factorial facts for kids

**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 . When *n* is a positive odd integer, is defined as . When n is an positive even integer, is defined as . By definition, .

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Double factorial Facts for Kids. *Kiddle Encyclopedia.*