# Talk:99 questions/Solutions/31

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Revision as of 11:14, 14 October 2013 by Mico wr (talk | contribs) (→And something as simple as this one...: new section)

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
```

## And something as simple as this one...

isPrime :: Int -> Bool isPrime n = all (\x -> n `mod`x /= 0) [2..sqr] where sqr = floor (sqrt (fromIntegral n :: Double))

-- Assuming that a number is not a prime if he is divisible by any number between 2 and his sqrt