Array Conversion Approach
This method involves calculating the factorial sequentially and using built-in JavaScript functions to convert the resultant number into an array of digits. The `reduce} method is then used to calculate the sum of these digits, which is straightforward but may result in cost from array formation.
Example: This example demonstrates how to calculate the factorial of a number and then convert it into an array of digits to compute their sum.
Javascript
function factorial(n) { let result = 1; for (let i = 2; i <= n; i++) { result *= i; } return result; } function sumOfDigitsInFactorial(num) { const fact = factorial(num); const digits = Array.from(String(fact), Number); return digits.reduce((sum, digit) => sum + digit, 0); } const number = 5; const sum = sumOfDigitsInFactorial(number); console.log( "Sum of digits in factorial:" , sum); |
Sum of digits in factorial: 3
JavaScript Program to Find the Sum of Digits in a Factorial
Let’s first define the problem before proceeding to a solution. Any positive number less than or equal to n is the product of all positive integers, and the factorial of a non-negative integer n is denoted by n!. For example, 5!, sometimes known as “five factorial,” is equivalent to 5 × 4 × 3 × 2 × 1 = 120. Adding up the digits of a given number’s factorial is our objective.
Examples:
Input: 10
Output: 27
Input: 100
Output: 648
These are the following appraoches:
Table of Content
- Iterative Approach
- Recursive Approach
- Array Conversion Approach