Write a Python program that asks the user for a positive, odd value. Once the value is validated determine if the number is Prime (i. e., divisible only by itself and 1.)

val = int(input("Enter a positive odd value "))

flag = True # let the number entered is alreay prime

if(val > 2 and val%2 == 1):  # prime numbers start from 2

   half = int(val/2);

   for div in range(2,half):  # dividing the number from 2 to half of its number

       if(val % div == 0): # if completely divisible

           print("Not prime")

           flag = False   # Changing the status of prime number as false

           break

   if(flag == True):

       print(val, "is a prime number")

else:

   print("Invalid input, Please Enter a valid positive odd number")

Explanation:

Steps:

1. Let us take input from the user using input() method.

2.  Initially, let the number is prime.

3. If the number is negative or even, the go to else part and ask the user for a valid input and terminate the program by giving a message to user.

(We actually check for values greater than 2 because 1 is not considered as  a prime number)

4. If the number is positive and odd, then we keep on dividing the number from 2 to half of its number.

(We actually check for values greater than 2 because 1 is not considered as  a prime number)

5. If the number is divisible, we change the status to False and break the loop.

6. If the flag is still True, we print that it is a Prime number else we print that it is not a prime number.

Please refer to the comments section as well and the attached image for proper indentation of the program.

1. entrepreneur.com

2. wikipedia