exercise_7.py

#Goldbach conjecture
#Every even number is the sum of two prime numbers
#This program gets a number from the user, validates it being even,
#then finds two primes that add up to that number

import math as m

def primeNum(n):
        #check if n is evenly divisible by values between 2 and int(m.sqrt(n))
        x = m.sqrt(n)
        i = 2
        while i <= x:
            value = n % i
            if value == 0:
                return None
            else:
                i = i + 1
        return n
def main():
    x = eval(input("Input a positive whole number: "))
    #Validate x as a positive whole number
    if x == 0:
        x = eval(input("Your number must be higher than 0: "))
    elif (x % 1 != 0):
        x = eval(input("The number you entered was not whole: "))
    elif (x < 1):
        x = eval(input("The number you entered was not positive: "))
    elif (x % 2 != 0):
        x = eval(input("The number you entered was not even: "))
    else:
        n = x
        while n > 0:
                prime = primeNum(n+1)
                if prime != None:
                        prime2 = x - prime
                        test = primeNum(prime2)
                        if test != None:
                            print("{0} + {1} = {2}".format(prime, prime2, x))
                n = n - 1 
                
main()