What is 18 factorial ?

Steps to calculate factorial of 18

To find 18 factorial, or 18!, simply use the formula that multiplies the number 18 by all positive whole numbers less than it.

Let’s look at how to calculate the Factorial of 18:

18! is exactly :
Factorial of 18 can be calculated as:
18! = 18 x 17 x 16 x 15 x 14 x 13 x 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1

Factorials of Numbers similar to 18

What is Factorial?

The term “factorial” in mathematics denotes the product of all positive integers up to a certain number, represented by that number followed by an exclamation point. The factorial of 18, indicated as “18!”, is significant because it represents a vast number of permutations, crucial in fields such as combinatorics, probability, and sequence design. Understanding 18! reveals the complexity of calculating combinations and permutations in larger sets, highlighting the factorial’s role in solving intricate mathematical problems.

Formula to Calculate the Factorial of 18

To calculate the factorial of a number, use the basic formula n! = n × (n-1) × … × 1. Applying this formula to 18, we calculate the factorial by multiplying all whole numbers from 18 down to 1. For example:

18! = 18 × 17 × 16 × … × 2 × 1.

This multiplication results in a rather large number, exemplifying the rapid growth of factorials as numbers increase.

What is the Factorial of 18 Used For?

The factorial of 18 has several intriguing applications. In combinatorics, it is used to calculate the number of ways to arrange or select 18 distinct items. In probability theory, it helps determine probabilities in scenarios with 18 possible outcomes or choices. Beyond mathematics, 18! may have applications in computer algorithms, such as those that handle large data permutations or organize complex system operations.


  • Calculate the last two digits of 18! without calculating the entire factorial.
  • Estimate the number of zeros at the end of the value 18!.
  • If a group of 18 people are to be seated in a row, in how many different ways can they be arranged?

Solutions to Exercises

Solution for Exercise 1: The last two digits of 18! can be calculated by identifying the multiples of 10 within the factorial sequence, which contribute to the trailing zeros. Factoring out the powers of 10 leaves us with the units of the remaining product, which are 80.

Solution for Exercise 2: The number of zeros at the end of 18! is determined by counting the number of fives (and corresponding twos), which total to 3, contributing to three trailing zeros.

Solution for Exercise 3: The arrangement of 18 people can be calculated by 18! which equals a large number beyond the scope of manual calculation, signifying 18 factorial ways they can be arranged.

Frequently Asked Questions

Q: What is the exact numerical value of 18 factorial?

A: The exact numerical value of 18 factorial is a very large number that is typically computed using a calculator or computer software due to its extensive length.

Q: Is there a simple way to compute large factorials like 18?

A: Large factorials are typically computed using computer algorithms or calculators with advanced functions, as manual computation can be very complex and time-consuming.

Other conversions of the number 18