1. http://www.pythonchallenge.com/
2. https://www.hackerrank.com/domains/python
3. https://www.hackerearth.com/practice/python/getting-started/numbers/practice-problems/
4. https://learnpython.org/
5. https://www.w3schools.com/python/python_exercises.asp
6. http://codingbat.com/python
7. https://pythonbasics.org/exercises/
8. https://www.geeksforgeeks.org/python-programming-language/learn-python-tutorial