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In this article
FACT returns n! (1 × 2 × … × n). It grows absurdly fast: FACT(20) is already about 2.4 quintillion.
Syntax
=FACT(number)| Argument | What it means |
|---|---|
number |
Non-negative; decimals are truncated. |
Examples
Example 1
=FACT(5)120 ways to order five books on a shelf.
Common errors and fixes
| You see | Why, and the fix |
|---|---|
#NUM! |
Negative input, or above 170 (the result overflows Excel’s number limit). |
FACT in practice
Where you will use it
- Number of seating arrangements
- Probability teaching
- Permutations by hand
Worked example
| n | Formula | Result |
|---|---|---|
| 5 | =FACT(A2) | 120 |
| 10 | =FACT(A3) | 3628800 |
| 0 | =FACT(A4) | 1 |
Results calculated in Excel.
Mistakes people make
| Mistake | What to do instead |
|---|---|
| Huge numbers | FACT(171) overflows; 170 is the limit |
| Negative input | Gives #NUM! |
Related functions
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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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