Question

How to sum the digit of a factorial of a number in Swift

Answer 1

func sumDigits(_ num: Int) -> Int {
    var sum = 0
    var n = num
    while n != 0 {
        sum += n % 10
        n /= 10
    }
    return sum
}

func factorial(_ n: Int) -> Int {
    if n == 1 || n == 0 {
        return 1
    }
    return n * factorial(n - 1)
}

let number = 9
let result = factorial(number)

print("factorial = \(result)")
print("sum digits = \(sumDigits(result))")



/*
run:

factorial = 362880
sum digits = 27

*/

 

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