```
# goldbach_conjecture.py
# The Goldbach conjecture asserts that every even number larger than 2 is the sum
# of two prime numbers.
# This program gets a number from the user, checks to make sure that it is
# even, then finds two prime numbers that add up to the number inputted.
# by: Scott Gordon
from math import sqrt
def is_prime(n):
"""Determines whether number (n) is prime or not"""
if n % 2 == 0 and n != 2:
return False
factor = 3
while factor <= sqrt(n):
if n % factor == 0:
return False
factor += 2
return True
def goldbach(x):
cand = 3
while cand < x/2:
other = x - cand
if is_prime(cand) and is_prime(other):
return cand
else:
cand = cand + 2
def main():
print("Goldbach Conjecture Calculator\n")
num = int(input("Enter an even natural number: "))
if num % 2 != 0:
print(f"{num} is not even!")
else:
prime1 = goldbach(num)
prime2 = num - prime1
print(f"{prime1} + {prime2} = {num}")
if __name__ == '__main__':
main()
```

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