FACTORIAL

Factorial

Definition Of Factorial

Factorial denoted as n!, with n > 0, is an expression, which is the product of all positive
integers starting with n and counting backward to 1.
For example, 4! = 4 . 3 . 2 . 1 and
n! = n . n-1 . n-2 . . . . 3. 2. 1

More About Factorial

By definition, factorial of zero is 1. That is, 0! = 1

Video Examples:Factorials - Evaluating Factorials! Basic Info

Solved Example on Factorial

Ques: Find the factorial of 8.

Choices:

A. 40,320
B. 40,230
C. 41,320
D. 41,230
Correct Answer: A

Solution:

Step 1: Factorial of 8 is 8 × 7 × 6 × 5 × 4 × 3 × 2 × 1 = 40,320.

Quick Summary

Factorial of n (n!) is the product of all positive integers from 1 to n.
0! is defined as 1.
Factorials grow very quickly as n increases.

\[ n! = n \times (n-1) \times (n-2) \times ... \times 2 \times 1 \]

🍎 Teacher Insights

Use visual aids to demonstrate the concept of factorials. Emphasize the importance of understanding the definition and practicing calculations. Relate factorial to permutations and combinations.

🎓 Prerequisites

Multiplication
Integers

Check Your Knowledge

Q1: What is the value of 5!?

A. 15 B. 24 C. 120 D. 720

Q2: Which of the following is equal to 1?

A. 1! B. 0! C. Both A and B D. None of the above

Frequently Asked Questions

Q: What is 0!?
A: 0! is defined as 1.

Q: How do I calculate a factorial?
A: Multiply all positive integers from 1 up to the number you are finding the factorial of.