Problem 10：Summation of primes

题目描述：

The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

Find the sum of all the primes below two million.

代码：

import math
def isPrinmer(num):
	ret=True
	for i in range(2,int(math.sqrt(num)+1)):
		if num%i==0:
			ret=False
			return ret
	return ret

sum=0
for i in range(2,2000001):
	if isPrinmer(i):
		sum+=i
print sum