#Find the sum of all the primes below two million.

from math import sqrt
import time

#this function will determine if 
# num is prime
def nextPrime(num):
            
    isPrime = False
    while not isPrime:
        numSqrt = sqrt(num)
        isPrime = True
        i = 2
        
        while i <= numSqrt and isPrime:
            if num % i == 0:
                isPrime = False
            
            i += 1
            
        if not isPrime:    
            num += 1
              
    return num 

curNum = 2
MAX_NUM = 2000000
sumOfPrimes = 0
startTime = time.time()

print "Calculating the sum of primes below %d" % (MAX_NUM,)

while True:
    #Only check odd numbers that are greater than 2
    curNum = nextPrime(curNum)
    if curNum < MAX_NUM:
        sumOfPrimes += curNum
    else:
        break
    
    if curNum <= 2:
        curNum +=1
    else:
        curNum += 2
    
endTime = time.time()

print 'calculation took %0.3f ms' % ((endTime-startTime)*1000.0,)
   
print "The sum of all primes below %d is %d" % (MAX_NUM,sumOfPrimes)