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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

GCD of Two Numbers (Loop) in Python

Compute the greatest common divisor (GCD) of two integers using the Euclidean algorithm.

BeginnerLoop ProgramsExample 10 of 25
gcd-of-two-numbers-loop.py
1# Program to find GCD of two numbers using Euclidean algorithm
2

3a = int(input("Enter first integer: "))
4b = int(input("Enter second integer: "))
5

6while b != 0:
7    a, b = b, a % b
8

9print("GCD is", abs(a))

Output

Enter first integer: 54
Enter second integer: 24
GCD is 6

What's going on

We repeatedly replace (a, b) with (b, a % b) until b becomes 0; the remaining a is the GCD.

After this program

If the idea is still fuzzy, read Day 9: Loops and Iteration in the Python course. For a short check, try the Python quiz (300 questions). Stay with all 25 loop programs, or see every topic on Python exercises.

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