by July 17, 2012

onThis would be the factorial implementation in Scala combined with a small function to sum the single digits of the resulting number.

```
class Euler020 extends Euler {
def number = 20
def solution = {
def factorial(n: Int) = {
def inner(i: Int, current: BigInt): BigInt = {
i match {
case 1 => current
case _ => inner(i - 1, current * i)
}
}
inner(n, 1)
}
val fact = factorial(100).toString()
fact.foldLeft(0)((s, c) => s + Character.getNumericValue(c))
}
}
```