Factorial of a Given Number

Definition

The factorial of a number is the product of all positive integers from 1 to that number.

Formula

For a number n:

5! = 5 × 4 × 3 × 2 × 1 = 120
4! = 4 × 3 × 2 × 1 = 24.

Algorithm:

1.Start

2.Read the number n

3.Initialize fact = 1 and i = 1

4.Check whether i <= n

5.Multiply fact by i

6.Increment i by 1

7.Repeat steps 4 to 6 until i > n

8.Print the factorial value

9.Stop

Flowchart:

Start
|
Input n
|
fact = 1
i = 1
|
i <= n ?
/ \
Y N
| |
fact=fact*i
|
i=i+1
|
Back to i<=n

N
|
Print Factorial
|
Stop

code:

n = int(input("Enter a number: "))

fact = 1
i = 1

while i <= n:
    fact = fact * i
    i += 1

print("Factorial =", fact)

Input:

Enter a number: 5

Output:

Factorial = 120