Apple iWork '09 - Manual (Page 175)

Chapter 8 Numeric Functions 175
Related Topics
For related functions and additional information, see:
“FACTDOUBLE” on page 175
“MULTINOMIAL” on page 184
“Listing of Numeric Functions” on page 167
“Value Types” on page 36
“The Elements of Formulas” on page 15
“Using the Keyboard and Mouse to Create and Edit Formulas” on page 26
“Pasting from Examples in Help” on page 41
FACTDOUBLE
The FACTDOUBLE function returns the double factorial of a number.
FACTDOUBLE(fact-num)
 fact-num: A number. fact-num is a number value and must be greater than or equal
to –1. Values in the range –1 to 1 return 1. Any decimal (fractional) part of fact-num is
ignored.
Usage Notes
For an even integer, the double factorial is the product of all even integers less than Â
or equal to the given integer and greater than or equal to 2. For an odd integer, the
double factorial is the product of all odd integers less than or equal to the given
integer and greater than or equal to 1.
Examples
=FACTDOUBLE(4) returns 8, the product of 2 and 4.
=FACTDOUBLE(4.7) returns 8, the product of 2 and 4. The decimal portion is ignored.
=FACTDOUBLE (10) returns 3840, the product of 2, 4, 6, 8, and 10.
=FACTDOUBLE(1) returns 1, as all numbers between –1 and 1 return 1.
=FACTDOUBLE(-1) returns 1, as all numbers between –1 and 1 return 1.
=FACTDOUBLE (7) returns 105, the product of 1, 3, 5, and 7.
Related Topics
For related functions and additional information, see:
“FACT” on page 174
“MULTINOMIAL” on page 184