Hi everyone. I'm new(ish) to C# and i've decided to hone my skills in windows forms applications. I've got stuck on this question and would really appreciate some expertise from you guys:

**"The prime factors of 13195 are 5, 7, 13 and 29.**

What is the largest prime factor of the number 600851475143?"

The question is taken from projecteuler.net which has some challenging problems on their (not an advertisement) just saying incase anyone didn't know about the site. I've created this method which doesn't work around the while loop. The math.Round(i) doesn't work because i don't know how to use it, I read somewhere that it collects only whole numbers but I am unsure what I should be referencing.

```
private static long question3()
{
long bigNum = 600851475143;
int x = 1;
while (bigNum == Math.Round(bigNum))
{
bigNum /= x;
x++;
}
return (bigNum);
}
```

What i'm trying to do is to get this method to break down the 600851475143 then extract the largest whole number. I then wanted to put the largest whole varible into another method which would then further break down the number into its highest prime factor. I'm sure theres an easier way to do this, but please understand that i'm just practising and making mistakes as I go whilst trying to figure them out myself, but this has made me very confused. I would greatly appreciate help from you guys and maybe you could tell me the way you would tackle this problem. Thanks.