The FACTDOUBLE function returns the double factorial of a number.
FACTDOUBLE(fact-num)
fact-num: A number value. fact-num must be greater than or equal to –1. Values in the range –1 to 1 return 1. Any decimal part of fact-num is ignored.
Notes
For an even integer, the double factorial is the product of all even integers less than 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 |
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=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 3,840, the product of 2, 4, 6, 8, and 10. =FACTDOUBLE(1) returns 1, because all numbers between -1 and 1 return 1. =FACTDOUBLE(-1) returns 1, because all numbers between -1 and 1 return 1. =FACTDOUBLE (7) returns 105, the product of 1, 3, 5, and 7. |