86 lines
1.7 KiB
Markdown
86 lines
1.7 KiB
Markdown
---
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id: 5900f3711000cf542c50fe84
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challengeType: 5
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title: 'Problem 5: Smallest multiple'
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forumTopicId: 302160
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---
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## Description
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<section id='description'>
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2520 is the smallest number that can be divided by each of the numbers from 1 to 10 without any remainder.
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What is the smallest positive number that is evenly divisible by all of the numbers from 1 to `n`?
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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>smallestMult(5)</code> should return a number.
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testString: assert(typeof smallestMult(5) === 'number');
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- text: <code>smallestMult(5)</code> should return 60.
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testString: assert.strictEqual(smallestMult(5), 60);
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- text: <code>smallestMult(7)</code> should return 420.
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testString: assert.strictEqual(smallestMult(7), 420);
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- text: <code>smallestMult(10)</code> should return 2520.
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testString: assert.strictEqual(smallestMult(10), 2520);
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- text: <code>smallestMult(13)</code> should return 360360.
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testString: assert.strictEqual(smallestMult(13), 360360);
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- text: <code>smallestMult(20)</code> should return 232792560.
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testString: assert.strictEqual(smallestMult(20), 232792560);
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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 smallestMult(n) {
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return true;
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}
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smallestMult(20);
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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 smallestMult(n){
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function gcd(a, b) {
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return b === 0 ? a : gcd(b, a%b); // Euclidean algorithm
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}
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function lcm(a, b) {
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return a * b / gcd(a, b);
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}
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var result = 1;
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for(var i = 2; i <= n; i++) {
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result = lcm(result, i);
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}
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return result;
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}
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```
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</section>
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