FACTDOUBLE Function in Excel: Double Factorial

FACTDOUBLE Function in Excel: Double Factorial featured illustration

📎 This article includes 1 downloadable practice file ↓

⏱ 2 min readUpdated 28 September 2026

MathLevel: ExpertAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. FACTDOUBLE in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions
  9. Continue learning

FACTDOUBLE multiplies every other number: 7!! = 7 × 5 × 3 × 1.

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Syntax

=FACTDOUBLE(number)
Argument What it means
number Non-negative.

Examples

Example 1

=FACTDOUBLE(7)

Returns 105 — also the number of ways to pair up 8 people.

FACTDOUBLE in practice

Where you will use it

  • Double factorial in probability formulas
  • Physics and combinatorics
  • Teaching

Worked example

nFormulaResult
6=FACTDOUBLE(A2)48
7=FACTDOUBLE(A3)105
10=FACTDOUBLE(A4)3840

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Confusing with FACT6!! = 6×4×2, not 6!×2
Negative input#NUM!

FACT

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📎 Practice files for this article

  • 📗
    Practice workbook: Math & rounding24 tasks on realistic sales data — type your formula, the Check column turns green when it is right. Answers sheet included.
    ⬇ XLSX · 35 KB

Free to use for learning. Files with macros (.bas) are plain text — import them with Alt+F11 → File → Import File, and always test on a copy.

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