# Untitled

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Aug 25th, 2019
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1. #Find prime factors in python
2. from math import sqrt
3.
4. def primality_testing(n):
5. """test if the given number is prime or not"""
6. if type(n) != int:
7. print("the given number is not a positive integer")
8. elif n == 1:
9. return False
10. elif n == 2:
11. return True
12. elif n == 3: #exception occurs when n == 3
13. return True
14. elif n > 2:
15. if int(sqrt(n)) > 2:
16. for i in range(2, int(sqrt(n))):
17. b = n % i #Check if the modulo of n against a trial division number i is 0
18. if b == 0:
19. return False #if modulo is zero, then the given number is a factor, so n is not a prime number
20. return True #if modulo is not zero, then the given number is not a factor, so n is a prime number
21. elif int(sqrt(n)) == 2: #taking out the exceptional case when sqrt(n) = 2
22. b = n % 2 #the trial division number here is 2
23. if b == 0:
24. return False
25. return True
26.
27. is_prime = primality_testing(13)
28. print(is_prime)
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