# FACTDOUBLE function

This article describes the formula syntax and usage of the FACTDOUBLE function in Microsoft Excel.

## Description

Returns the double factorial of a number.

## Syntax

FACTDOUBLE(number)

The FACTDOUBLE function syntax has the following arguments:

• Number    Required. The value for which to return the double factorial. If number is not an integer, it is truncated.

## Remarks

• If number is nonnumeric, FACTDOUBLE returns the #VALUE! error value.

• If number is negative, FACTDOUBLE returns the #NUM! error value.

• If number is even: • If number is odd: ## Example

Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.

Formula

Description

Result

=FACTDOUBLE(6)

Double factorial of 6. For 6, an even number, the double factorial is equivalent to 6*4*2; using this equation:

n!! = n*(n-2)*(n-4)...(4)(2)

48

=FACTDOUBLE(7)

Double factorial of 7. For 7, an odd number, the double factorial is equivalent to 7*5*3; using this equation:

n!! = n*(n-2)*(n-4)...(3)(1)

105

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