WCW

# Project Eurler Problem 10

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

```