Prime factor of 300 000 000 000?

Question

I need to find out the prime factors of over 300 billion. I have a function that is adding to the list of them...very slowly! It has been running for about an hour now and i

Answer 1

Are you remembering to divide the number that you're factorizing by each factor as you find them?

Say, for example, you find that 2 is a factor. You can add that to your list of factors, but then you divide the number that you're trying to factorise by that value.

Now you're only searching for the factors of 150 billion. Each time around you should start from the factor you just found. So if 2 was a factor, test 2 again. If the next factor you find is 3, there's no point testing from 2 again.

And so on...