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# airflow's solution

## to Armstrong Numbers in the JavaScript Track

Published at May 02 2021 · 0 comments
Instructions
Test suite
Solution

An Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits.

For example:

• 9 is an Armstrong number, because `9 = 9^1 = 9`
• 10 is not an Armstrong number, because `10 != 1^2 + 0^2 = 1`
• 153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
• 154 is not an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`

Write some code to determine whether a number is an Armstrong number.

## Setup

Go through the setup instructions for Javascript to install the necessary dependencies:

https://exercism.io/tracks/javascript/installation

## Requirements

Please `cd` into exercise directory before running all below commands.

Install assignment dependencies:

``````\$ npm install
``````

## Making the test suite pass

Execute the tests with:

``````\$ npm test
``````

In the test suites all tests but the first have been skipped.

Once you get a test passing, you can enable the next one by changing `xtest` to `test`.

## Submitting Solutions

Once you have a solution ready, you can submit it using:

``````exercism submit armstrong-numbers.js
``````

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

## Exercise Source Credits

### armstrong-numbers.spec.js

``````import { isArmstrongNumber } from './armstrong-numbers';

describe('Armstrong Numbers', () => {
test('Zero is an Armstrong number', () => {
expect(isArmstrongNumber(0)).toEqual(true);
});

xtest('Single digit numbers are Armstrong numbers', () => {
expect(isArmstrongNumber(5)).toEqual(true);
});

xtest('There are no 2 digit Armstrong numbers', () => {
expect(isArmstrongNumber(10)).toEqual(false);
});

xtest('Three digit number that is an Armstrong number', () => {
expect(isArmstrongNumber(153)).toEqual(true);
});

xtest('Three digit number that is not an Armstrong number', () => {
expect(isArmstrongNumber(100)).toEqual(false);
});

xtest('Four digit number that is an Armstrong number', () => {
expect(isArmstrongNumber(9474)).toEqual(true);
});

xtest('Four digit number that is not an Armstrong number', () => {
expect(isArmstrongNumber(9475)).toEqual(false);
});

xtest('Seven digit number that is an Armstrong number', () => {
expect(isArmstrongNumber(9926315)).toEqual(true);
});

xtest('Seven digit number that is not an Armstrong number', () => {
expect(isArmstrongNumber(9926314)).toEqual(false);
});
});``````
``````/******************************************************************************
9 is an Armstrong number, because `9 = 9^1 = 9`
10 is *not* an Armstrong number, because `10 != 1^2 + 0^2 = 1`
153 is an Armstrong number, because: `153 = 1^3 + 5^3 + 3^3 = 1 + 125 + 27 = 153`
154 is *not* an Armstrong number, because: `154 != 1^3 + 5^3 + 4^3 = 1 + 125 + 64 = 190`
******************************************************************************/

export const isArmstrongNumber = number => {

let num    = number.toString();
let digits = num.length;
// console.log(digits);
let check = 0;

for (let i = 0; i < digits; i++)
check += num[i] ** digits;

return number == check;

};``````