Excel FactDouble function is used to returns the double factorial of given positive number. The FactDouble function in Excel is located in the Math & Trig category. The double factorial of any positive number is equal to 6*4*2…. number, while for any negative number is equal to 5*3*1.. If you need to quickly calculate double factorial of any large even or odd number then you can use Excel FactDouble function in active worksheet. In this article we have to describe the formula and how to use Excel FactDouble function.

The Microsoft Excel FactDouble function allows you to quickly returns the double factorial of any positive even or odd number. FactDouble is an important built-in function which is located in the Math & Trig category. This function can be used just like a worksheet (WS) function. You can use FactDouble function to get the double factorial either directly fill the number or use cell address in active worksheet. In our previous article we have already discuss about the Excel Fact function which returns factorial of given 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.

**Example**: Let’s look at some Excel FACTDOUBLE function examples and explore how to use the FACTDOUBLE function as a worksheet function in Microsoft Excel:

**Syntax**: =FACTDOUBLE(H116)

**Result**:

Based on the Excel spreadsheet above, the following FACTDOUBLE examples would return:

**Syntax**: =FACTDOUBLE(H117)

**Result**: 8

**Syntax**: =FACTDOUBLE(H118)

**Result**: 15

**Syntax**: =FACTDOUBLE(H119)

**Result**: 48

**Syntax**: =FACTDOUBLE(H120)

**Result**: 105

**Syntax**: =FACTDOUBLE(H121)

**Result**: 384

**Syntax**: =FACTDOUBLE(H122)

**Result**: 945

**Note**: The FACTDOUBLE function returns the double factorial of a number. A double factorial is calculated differently for even and odd numbers. For an even number, n, it’s the product of all even integers less than or equal to n and greater than or equal to 2. For an odd number, the double factorial is the product of all odd integers less than or equal to n and greater than or equal to 1. The double factorial for both zero and -1 are defined as 1. For numbers less than -1, a double factorial is not defined.