factorial

/fækˈtɔriəl/
noun
  1. The product of all positive integers from 1 up to a given number, often written with an exclamation mark (e.g., 5! = 5 × 4 × 3 × 2 × 1 = 120).
    • In math class, we learned how to calculate factorials for probability problems.
    • The factorial of 4 is 24.
    • The number of ways to arrange 6 books on a shelf is 6 factorial.
adjective
  1. Relating to a factorial or the product of a series of numbers.
    • The factorial function grows very quickly as the input increases.
    • We used a factorial design in the experiment to test multiple variables.
    • The factorial notation is a shorthand for multiplying a sequence of descending numbers.
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