How to calculate the 21! (21 factorial) in swift?

Question

I am making fuction that calculate factorial in swift. like this

func factorial(factorialNumber: UInt64) -> UInt64 {
    if factorialNumber == 0 {
                


        

Answer 1

Here's a function that accepts any type that conforms to the Numeric protocol, which are all builtin number types.

func factorial(_ x: N) -> N {
    x == 0 ? 1 : x * factorial(x - 1)
}