In mathematics, the factorial of a non-negative integer ‘n’ is the product of all positive integers less than or equal to ‘n’ It is denoted by n! Mathematically,
Python Program to Calculate Factorial:
Here’s a Python program that calculates the factorial of a given number:
num = int(input("Enter a number: "))
factorial = 1
if num < 0:
print("Factorial is not defined for negative numbers.")
elif num == 0:
print("Factorial of 0 is 1.")
for i in range(1, num + 1):
factorial *= i
print("Factorial of", num, "is", factorial)
- The program starts by taking an integer input from the user using the `input()` function and converting it into an integer using the `int()` function. This input is stored in the variable `num`.
- The variable `factorial` is initialized to 1. This will store the result of the factorial calculation.
- The program uses conditional statements (`if`, `elif`, and `else`) to handle different cases:
- If the input is negative, it prints that factorial is not defined for negative numbers.
- If the input is 0, it prints that the factorial of 0 is 1.
- Otherwise, it calculates the factorial using a `for` loop that iterates from 1 to `num + 1`, and at each step, updates the `factorial` by multiplying it with the current value of `i`.
- After the loop, the program prints the calculated factorial.
Enter a number: 5
Factorial of 5 is 120
In this example, if the user enters the number 5, the program calculates the factorial of 5 using the formula \( 5! = 5 \times 4 \times 3 \times 2 \times 1 = 120 ) and displays “Factorial of 5 is 120” as the output.