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1. Print Numbers 1–1002. Print Even Numbers in Range3. Print Odd Numbers in Range4. Sum of Digits5. Reverse Digits of a Number6. Calculate Factorial (Loop)7. Fibonacci Series8. Palindrome Number Check9. Count Digits in a Number10. GCD of Two Numbers (Loop)11. LCM of Two Numbers (Loop)12. Print Prime Numbers in Range13. Count Prime Numbers in Range14. Check Composite Number15. Power of 2 Checker16. Print Number Pattern17. Print Star Pattern18. Armstrong Numbers in Range19. Strong Numbers in Range20. Sum of Series 1/1 + 1/2 + … + 1/N21. Print Multiplication Series22. Print Pyramid Pattern23. Print Inverted Pyramid Pattern24. Print Floyd's Triangle25. Print Pascal's Triangle

Calculate Factorial (Loop) in Python

Calculate the factorial of a non-negative integer using a loop.

BeginnerLoop ProgramsExample 6 of 25
calculate-factorial-loop.py
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1# Program to calculate factorial using a loop
2

3n = int(input("Enter a non-negative integer: "))
4

5if n < 0:
6    print("Factorial is not defined for negative numbers.")
7else:
8    fact = 1
9    for i in range(1, n + 1):
10        fact *= i
11    print(f"Factorial of {n} is {fact}")

Output

Enter a non-negative integer: 5
Factorial of 5 is 120

What's going on

We multiply numbers from 1 to n in a loop to compute n! (factorial).

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