# Talk:99 questions/Solutions/31

From HaskellWiki

Does something as simple but as dump as this should be on the wiki ?

```
isPrime :: Int -> Bool
isPrime n | n <= 1 = False
isPrime n = isPrime' 2 n
where isPrime' x n | x*x > n = True
| otherwise = (n `rem` x) /= 0 && isPrime' (x+1) n
```