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    FACT

    Math & Trig

    Returns the factorial of a number (n! = n x (n-1) x ... x 1).

    Translations
    EnglishFACT
    FrenchFACT
    SpanishFACT
    GermanFAKULTÄT
    ItalianFATTORIALE
    PortugueseFATORIAL
    DutchFACULTEIT
    PolishSILNIA
    RussianФАКТР
    TurkishÇARPINIM
    CzechFAKTORIÁL
    HungarianFAKT
    SwedishFAKULTET
    DanishFAKULTET
    FinnishKERTOMA
    Syntax
    FACT(number)

    Arguments

    • numberNon-negative integer
    Examples
    =FACT(5)
    120

    5! = 5x4x3x2x1

    =FACT(0)
    1

    0! is defined as 1

    =FACT(10)
    3628800

    10 factorial

    Tips & Best Practices
    • •Used in probability and combinatorics
    • •FACT(170) is the largest Excel can handle
    • •Decimals are truncated before calculation
    Common Mistakes
    • •Passing a negative number to FACT, which returns a #NUM! error since factorial is only defined for non-negative numbers
    • •Passing a non-integer number expecting an error - FACT actually truncates the decimal portion first, so FACT(4.9) calculates the factorial of 4, not 5
    • •Using FACT on a large number without realizing how quickly factorials grow - FACT(170) is close to Excel's maximum representable number, and anything larger returns a #NUM! error from overflow
    Related Functions
    FACTDOUBLECalculates a double factorial (multiplying only every other integer) rather than FACT's standard factorial of every integer down to 1.
    COMBINUses factorial calculations internally to determine combinations, a common practical use case that builds on what FACT calculates.
    PERMUTAlso relies on factorial-based math to calculate permutations, another downstream use of the concept behind FACT.
    Frequently Asked Questions

    Why does FACT return a #NUM! error?

    Either the input is negative (factorial isn't defined for negative numbers) or it's large enough that the result overflows Excel's maximum representable number, which happens above 170.

    What does FACT do with a decimal number?

    It truncates the decimal portion first - FACT(4.9) calculates the factorial of 4, giving 24, not the factorial of 5.

    What is FACT(0)?

    1, by mathematical convention - the factorial of zero is defined as 1, not 0.

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