FACTDOUBLE takes just one argument, number, which should be a positive integer. If number is not an integer, the decimal portion of number will be removed before the factorial is calculated.

### Examples

For even numbers, the double factorial is the product of all even integers less than or equal to number and greater than or equal to 2. For example, the double factorial of 8 is 384: For odd numbers, the double factorial is the product of all odd integers less than or equal to number and greater than or equal to 1. The double factorial of 7 is 105: The double factorial for zero and -1 are defined as 1:

### Notes

If number is negative, FACTDOUBLE will return the #NUM! error. If number is not an integer it will be truncated to an integer, then solved. If number is not numeric, FACTDOUBLE will return the #VALUE! error.

### Dave Bruns

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