FACT Function in Excel: How to Calculate Factorials

Have you ever needed to calculate the factorial of a number in Excel?

For example, the factorial of 5 means multiplying 5 × 4 × 3 × 2 × 1, which gives 120. You can do this manually, but Excel has a built-in function that makes the calculation much easier.

The function is called FACT.

In this article, let’s learn how to use the FACT function in Excel with simple examples. We’ll also understand factorials, explore practical uses, compare FACT with other functions, and learn about common mistakes.

What Is the FACT Function in Excel?

The FACT function in Excel calculates the factorial of a number.

A factorial means multiplying a positive whole number by every positive whole number below it until you reach 1.

For example:

5! = 5 × 4 × 3 × 2 × 1 = 120

The exclamation mark (!) is the mathematical symbol used to represent a factorial.

Instead of multiplying these numbers manually, you can use the FACT function in Excel.

For example:

=FACT(5)
Result: 120

The FACT function is useful for mathematical calculations, probability, permutations, and combinations.

FACT Function Syntax in Excel:

The syntax of the FACT function is:

=FACT(number)

The function has one argument.

number: The nonnegative number for which you want to calculate the factorial.

You can enter a number directly or use a cell reference.

For example:

=FACT(5)

This calculates the factorial of 5 and returns 120.

You can also use a cell reference:

=FACT(A4)

If cell A4 contains 3, Excel returns 6.

Note: If you enter a positive decimal number, Excel removes the decimal part before calculating the factorial. For example, =FACT(4.8) returns the same result as =FACT(4), which is 24.

How to Use the FACT Function in Excel?

Let’s look at some simple examples to understand how the FACT function works.

Example 1: Calculate the Factorial of a Number

Suppose you want to calculate the factorial of 6.

Follow these steps:

1. Click an empty cell in your worksheet.

2. Enter the formula:

   =FACT(5)

3. Press Enter.

Excel returns 120.

This is because Excel calculates:

5 × 4 × 3 × 2 × 1 = 120

You don’t need to multiply the numbers manually. The FACT function does it for you.

Example 2: Calculate Factorials Using Cell References

You can also use the FACT function to calculate factorials for multiple numbers in a worksheet.

Suppose you enter the following values in column A.

Number	Formula	Result
1	=FACT(A2)	1
2	=FACT(A3)	2
3	=FACT(A4)	6
4	=FACT(A5)	24
5	=FACT(A6)	120
6	=FACT(A7)	720

To calculate the factorial of the number in cell A2:

1. Click cell B2.

2. Enter =FACT(A2).

3. Press Enter.

4. Drag the fill handle down to apply the formula to the remaining rows.

Excel calculates the factorial for each number using the corresponding cell reference.

This method is useful when you need to calculate factorials for a long list of numbers.

Example 3: Calculate the Factorial of Zero

You might expect the factorial of zero to be zero. However, in mathematics, the factorial of zero is defined as 1.

Excel follows the same rule.

Enter the formula:

=FACT(0)

Excel returns 1.

This result is important in many mathematical formulas, including those used in counting and probability.

Example 4: Calculate the Factorial of a Decimal Number

The FACT function can also accept decimal numbers.

For example:

=FACT(4.8)

Excel ignores the decimal part and calculates the factorial of 4.

Result: 24

This is important to remember if your data contains decimal values. Excel truncates the number to an integer before calculating the factorial.

For example:

• =FACT(4.2) returns 24
• =FACT(4.8) returns 24
• =FACT(5.9) returns 120

If you want to round a decimal number before calculating its factorial, you can use the ROUND function.

For example:

=FACT(ROUND(4.8,0))

Result: `120`

Here, ROUND(4.8,0) rounds 4.8 to 5. The FACT function then calculates the factorial of 5, which is 120.

Remember that =FACT(4.8) returns 24 because FACT truncates the decimal part, while =FACT(ROUND(4.8,0)) returns 120 because ROUND first rounds the number to 5.

Example 5: Calculate the Factorial of a Larger Number

The FACT function can calculate factorials for larger numbers as well.

For example:

Formula	Result
=FACT(7)	5040
=FACT(8)	40320
=FACT(9)	362880
=FACT(10)	3628800

Notice how quickly the results increase as the number gets larger.

This is a key feature of factorials. Even a small increase in the original number can produce a much larger result.

Practical Example: Calculate Possible Arrangements

The FACT function can help you calculate how many ways a set of items can be arranged.

Suppose you have 4 different books and want to arrange all of them in a row.

The number of possible arrangements is:

4! = 4 × 3 × 2 × 1 = 24

In Excel, enter:

=FACT(4)

Result: 24 possible arrangements

This works when all four books are different and you want to arrange every book.

The FACT function is also useful in probability, permutations, and combinations, where factorials are used in mathematical formulas.

Important: The FACT function calculates the factorial itself. More complex counting problems may require other functions or formulas, depending on the conditions.

What Is the Difference Between FACT and POWER in Excel?

The FACT and POWER functions perform different calculations.

Function	Purpose	Example	Result
FACT	Calculates a factorial	=FACT(5)	120
POWER	Raises a number to a specified power	=POWER(5,3)	125
Caret operator (^)	Raises a number to a power	=5^3	125

For example, =FACT(5) calculates:

5 × 4 × 3 × 2 × 1 = 120

However, =POWER(5,3) calculates:

5 × 5 × 5 = 125

Although both functions involve multiplication, they follow different mathematical rules.

Use FACT when you need a factorial. Use POWER or the caret operator when you need to raise a number to a power.

Important Things to Remember When Using FACT:

Here are a few points to keep in mind:

• Zero factorial: =FACT(0) returns 1.

• Positive whole numbers: The FACT function calculates the factorial of a nonnegative whole number.

• Decimal numbers: Excel removes the decimal part before calculating the factorial. For example, =FACT(4.8) returns 24.

• Negative numbers: The FACT function returns a NUM! error for negative numbers.

• Large numbers: Factorial results grow very quickly. Extremely large factorials can exceed Excel’s numerical limits and return a NUM! error.

Understanding these points will help you use the FACT function correctly.

Frequently Asked Questions:

1. What does the FACT function do in Excel?

The FACT function calculates the factorial of a number by multiplying it by every positive whole number below it down to 1.

For example, =FACT(5) returns 120.

2. What is the formula for FACT in Excel?

The formula is:

=FACT(number)

Replace number with the value or cell reference for which you want to calculate the factorial.

For example, =FACT(A2) calculates the factorial of the number in cell A2.

3. What is the result of FACT(0) in Excel?

The formula =FACT(0) returns 1.

In mathematics, zero factorial is defined as 1.

4. Can the FACT function calculate negative numbers?

No. If you enter a negative number, Excel returns a NUM! error.

For example, =FACT(-3) returns an error because factorials in Excel are defined for nonnegative numbers.

5. Can I use decimal numbers with the FACT function?

Yes. Excel removes the decimal part before calculating the factorial.

For example, =FACT(4.8) returns 24, which is the factorial of 4.

6. Where is the FACT function used?

The FACT function is used in mathematical calculations involving factorials. It can also help solve counting problems involving arrangements, permutations, and certain statistical calculations.

7. What is the difference between FACT and POWER?

FACT calculates a factorial, while POWER raises a number to a specified exponent.

For example, =FACT(4) returns 24, whereas =POWER(4,3) returns 64.

8. What is the difference between FACT and FACTDOUBLE in Excel?

The FACT function calculates the factorial by multiplying all positive whole numbers from the given number down to 1.

The FACTDOUBLE function calculates the double factorial, which multiplies numbers by skipping every other integer.

For example:

=FACT(5) returns 120 because 5 × 4 × 3 × 2 × 1 = 120.

=FACTDOUBLE(5) returns 15 because 5 × 3 × 1 = 15.

Use FACT for ordinary factorial calculations and FACTDOUBLE when you specifically need a double factorial.

Final Thoughts:

The FACT function in Excel makes it easy to calculate factorials without multiplying numbers manually.

You can use it to solve mathematical problems, calculate factorial values for a list of numbers, and work with counting arrangements.

The most important thing to remember is that a factorial multiplies a number by every positive whole number below it until it reaches 1.

Just remember that FACT accepts non-negative numbers, returns 1 for zero, and truncates decimal values before calculating the factorial.

Once you understand how factorials work, using the FACT function in Excel becomes simple and straightforward.

You can also explore our Advanced Functions in Excel Complete Guide to learn more about useful Excel functions