Question

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

Answer 1

function sumDigits(num: number) : number {
    let sum: number = 0;
 
    while (num != 0) {
        sum += num % 10;
        num = Math.floor(num / 10);
    }
 
    return sum;
}
 
function factorial(n: number) : number {
    if (n === 1 || n === 0) {
        return 1;
    }
    return n * factorial(n - 1);
}
 
const num: number = 9;
const result: number = factorial(num);
 
console.log("factorial = " + result);
console.log("sum digits = " + sumDigits(result));
 
 
 
/*
run:
 
"factorial = 362880" 
"sum digits = 27" 
 
*/

 

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