Here’s the problem:

Find the sum of all primes less than 2,000,000

projecteuler.net/problem=10

My solution:

# Author: Will Clausen # # Date: Jan 7, 2013 # # This program will solve Problem 10 from Project Euler. # The code is basically the same as the code for Problem 7. import math # Find the sum of all the primes below two million def problem10(): # 2 is the first prime number, so start there sum = 2 # The next number to check is 3 num = 3 # While there are still numbers to check while num < 2000000: # If the number is prime if isPrime(num): # Add the number to the total sum += num # And increment by 2 (since even numbers above 2 aren't prime) num += 2 return sum # Simple function to determine if a number is prime. Not super fast, # but will work for this problem because the numbers aren't super huge. def isPrime(Num): # Bound for divisors to check sqrtNum = int(math.sqrt(Num)) + 1 # Only need to check if the number is divisible by odd numbers, so # do that in the range function for x in range(3, sqrtNum, 2): if Num % x == 0: return False return True