Syntax. FACTDOUBLE(number)
Definition. This function returns the double factorial of a number.
Argument
number (required) The value for which to return the double factorial. If number isn’t an integer, the decimal places are truncated.
Background. The factorial n! of number n is defined as follows:
n! = n(n – 1)(n – 2)...(3)(2)(1)
The FACTDOUBLE() function for even numbers is defined as follows:
n!! = n(n – 2)(n – 4)...(4)(2)
and for odd numbers:
n!! = n(n – 2)(n – 4)...(3)(1)
The FACTDOUBLE() function uses numeric values. If number isn’t a numeric value, the FACTDOUBLE() function returns the #VALUE!
error. If number is negative, FACTDOUBLE() returns the #NUM!
error value.
More examples:
=FACTDOUBLE(5)
returns 15
(=5 • 3 • 1).
=FACTDOUBLE(8)
returns 384
(=8 • 6 • 4 • 2).
Sample Files
Use the FACT worksheet in the Chapter16.xls or Chapter16.xlsx sample file. The sample files are found in the Chapter16 folder. For more information about the sample files, see the section titled Using the Sample Files.
18.226.34.25