Program 3

 3. Write a Python program to check whether a given number is prime or not

A positive integer greater than 1 which has no other factors except 1 and the number itself is 

called a prime number. 2, 3, 5, 7 etc. are prime numbers as they do not have any other factors. 

But 6 is not prime (it is composite) since, 2 x 3 = 6.

num = int(input("Enter a number: "))

flag = False

if num > 1:

     for i in range(2, num):

          if (num % i) == 0:

              flag = True

              break

if flag:

    print(num, "is not a prime number")

else:

    print(num, "is a prime number")

OUTPUT

Enter a number: 123

123 is not a prime number

Enter a number: 13

13 is a prime number