How can I make Python work faster?
<p>I am trying to calculate the sum of all the prime numbers below 2 million and since I had already written a function to find the prime numbers which are less than a given number, I simply wrote a new one that calls the older function and sum the items in that list.</p>

<p>But it seems like it's taking forever. How can I speed this code up?</p>

<pre><code>def find_primes(n):
    "Find the prime numbers below n"
    primes=[];
    for i in range(2,n):
        for fac in range (2,i):
            if i!=fac and i%fac == 0:
                break
        else:
            primes.append(i)
    return primes

def add_primes(m):
    "Sum all the prime numbers below m"
    newlist=find_primes(m);
    t=sum(newlist);
    return t
</code></pre>

<p>PS: I'm kind of a novice about Python, so I will be glad if you can nicely explain my mistakes. Thanks in advance.</p>
