84 lines
2.5 KiB
Markdown
84 lines
2.5 KiB
Markdown
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---
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title: Iterated digits squaring
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id: 5a23c84252665b21eecc7ec1
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challengeType: 5
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---
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## Description
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<section id='description'>
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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:
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<pre>15 -> 26 -> 40 -> 16 -> 37 -> 58 -> 89
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7 -> 49 -> 97 -> 130 -> 10 -> 1</pre>
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Write a function that takes a number as a parameter and returns 1 or 89 after performing the mentioned process.
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</section>
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## Instructions
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<section id='instructions'>
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</section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: '''<code>iteratedSquare</code> should be a function.'''
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testString: 'assert(typeof iteratedSquare==''function'',''<code>iteratedSquare</code> should be a function.'');'
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- text: '''<code>iteratedSquare(4)</code> should return a number.'''
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testString: 'assert(typeof iteratedSquare(4)==''number'',''<code>iteratedSquare(4)</code> should return a number.'');'
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- text: '''<code>iteratedSquare(4)</code> should return <code>89</code>.'''
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testString: 'assert.equal(iteratedSquare(4),89,''<code>iteratedSquare(4)</code> should return <code>89</code>.'');'
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- text: '''<code>iteratedSquare(7)</code> should return <code>1</code>.'''
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testString: 'assert.equal(iteratedSquare(7),1,''<code>iteratedSquare(7)</code> should return <code>1</code>.'');'
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- text: '''<code>iteratedSquare(15)</code> should return <code>89</code>.'''
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testString: 'assert.equal(iteratedSquare(15),89,''<code>iteratedSquare(15)</code> should return <code>89</code>.'');'
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- text: '''<code>iteratedSquare(20)</code> should return <code>89</code>.'''
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testString: 'assert.equal(iteratedSquare(20),89,''<code>iteratedSquare(20)</code> should return <code>89</code>.'');'
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- text: '''<code>iteratedSquare(70)</code> should return <code>1</code>.'''
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testString: 'assert.equal(iteratedSquare(70),1,''<code>iteratedSquare(70)</code> should return <code>1</code>.'');'
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- text: '''<code>iteratedSquare(100)</code> should return <code>1</code>.'''
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testString: 'assert.equal(iteratedSquare(100),1,''<code>iteratedSquare(100)</code> should return <code>1</code>.'');'
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='js-seed'>
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```js
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function iteratedSquare (n) {
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// Good luck!
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}
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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function iteratedSquare (n) {
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var total;
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while (n != 89 && n != 1) {
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total = 0;
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while (n > 0) {
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total += Math.pow(n % 10, 2);
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n = Math.floor(n/10);
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}
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n = total;
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}
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return n;
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}
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```
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</section>
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