Check Disarium number - JavaScript

A Disarium number is a number where the sum of its digits raised to their respective positions equals the original number.

Definition

For a number with digits xy...z, it's a Disarium number if:

xy...z = x^1 + y^2 + ... + z^n

Where n is the total number of digits in the number.

Example

Let's check if 175 is a Disarium number:

175 = 1^1 + 7^2 + 5^3 = 1 + 49 + 125 = 175

Since the sum equals the original number, 175 is a Disarium number.

JavaScript Implementation

const num = 175;
const isDisarium = num => {
    const res = String(num)
    .split("")
    .reduce((acc, val, ind) => {
        acc += Math.pow(+val, ind+1);
        return acc;
    }, 0);
    return res === num;
};

console.log(isDisarium(num));
console.log(isDisarium(32));
console.log(isDisarium(4334));

true
false
false

How It Works

The function converts the number to a string, splits it into individual digits, and uses reduce to calculate the sum of each digit raised to its position (starting from 1). Finally, it compares this sum with the original number.

Alternative Approach

function checkDisarium(num) {
    let digits = num.toString().split('');
    let sum = 0;
    
    for (let i = 0; i 

true
true
true


Conclusion

Disarium numbers are identified by checking if the sum of digits raised to their positions equals the original number. Both functional and iterative approaches work effectively for this calculation.