freeCodeCamp/curriculum/challenges/english/08-coding-interview-prep/rosetta-code/iterated-digits-squaring.english.md

title	id	challengeType
Iterated digits squaring	5a23c84252665b21eecc7ec1	5

Description

If you add the square of the digits of a Natural number (an integer bigger than zero), you always end with either 1 or 89:

15 -> 26 -> 40 -> 16 -> 37 -> 58 -> 89
7 -> 49 -> 97 -> 130 -> 10 -> 1

Write a function that takes a number as a parameter and returns 1 or 89 after performing the mentioned process.

Instructions

Tests

tests:
  - text: <code>iteratedSquare</code> should be a function.
    testString: 'assert(typeof iteratedSquare=="function","<code>iteratedSquare</code> should be a function.");'
  - text: <code>iteratedSquare(4)</code> should return a number.
    testString: 'assert(typeof iteratedSquare(4)=="number","<code>iteratedSquare(4)</code> should return a number.");'
  - text: <code>iteratedSquare(4)</code> should return <code>89</code>.
    testString: 'assert.equal(iteratedSquare(4),89,"<code>iteratedSquare(4)</code> should return <code>89</code>.");'
  - text: <code>iteratedSquare(7)</code> should return <code>1</code>.
    testString: 'assert.equal(iteratedSquare(7),1,"<code>iteratedSquare(7)</code> should return <code>1</code>.");'
  - text: <code>iteratedSquare(15)</code> should return <code>89</code>.
    testString: 'assert.equal(iteratedSquare(15),89,"<code>iteratedSquare(15)</code> should return <code>89</code>.");'
  - text: <code>iteratedSquare(20)</code> should return <code>89</code>.
    testString: 'assert.equal(iteratedSquare(20),89,"<code>iteratedSquare(20)</code> should return <code>89</code>.");'
  - text: <code>iteratedSquare(70)</code> should return <code>1</code>.
    testString: 'assert.equal(iteratedSquare(70),1,"<code>iteratedSquare(70)</code> should return <code>1</code>.");'
  - text: <code>iteratedSquare(100)</code> should return <code>1</code>.
    testString: 'assert.equal(iteratedSquare(100),1,"<code>iteratedSquare(100)</code> should return <code>1</code>.");'

Challenge Seed

function iteratedSquare (n) {
  // Good luck!
}

Solution

function iteratedSquare (n) {
	var total;
	while (n != 89 && n != 1) {
		total = 0;
		while (n > 0) {
			total += Math.pow(n % 10, 2);
			n = Math.floor(n/10);
		}
		n = total;
	}
	return n;
}