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* rearrange some deck chairs --------- Co-authored-by: Muhammed Mustafa <muhammed@freecodecamp.org>
90 lines
2.2 KiB
Markdown
90 lines
2.2 KiB
Markdown
---
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id: cf1111c1c12feddfaeb1bdef
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title: Generate Random Whole Numbers with JavaScript
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challengeType: 1
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videoUrl: 'https://scrimba.com/c/cRn6bfr'
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forumTopicId: 18186
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dashedName: generate-random-whole-numbers-with-javascript
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---
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# --description--
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You can generate random decimal numbers with `Math.random()`, but sometimes you need to generate random whole numbers. The following process will give you a random whole number less than `20`:
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1. Use `Math.random()` to generate a random decimal number.
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2. Multiply that random decimal number by `20`.
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3. Use `Math.floor()` to round this number down to its nearest whole number.
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Remember that `Math.random()` can never quite return a `1`, so it's impossible to actually get `20` since you are rounding down with `Math.floor()`. This process will give you a random whole number in the range from `0` to `19`.
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Putting everything together, this is what your code looks like:
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```js
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Math.floor(Math.random() * 20);
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```
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You are calling `Math.random()`, multiplying the result by 20, then passing the value to `Math.floor()` to round the value down to the nearest whole number.
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# --instructions--
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Use this technique to generate and return a random whole number in the range from `0` to `9`.
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# --hints--
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The result of `randomWholeNum` should be a whole number.
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```js
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assert(
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typeof randomWholeNum() === 'number' &&
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(function () {
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var r = randomWholeNum();
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return Math.floor(r) === r;
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})()
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);
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```
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You should use `Math.random` to generate a random number.
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```js
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assert(code.match(/Math.random/g).length >= 1);
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```
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You should have multiplied the result of `Math.random` by 10 to make it a number in the range from zero to nine.
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```js
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assert(
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code.match(/\s*?Math.random\s*?\(\s*?\)\s*?\*\s*?10[\D]\s*?/g) ||
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code.match(/\s*?10\s*?\*\s*?Math.random\s*?\(\s*?\)\s*?/g)
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);
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```
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You should use `Math.floor` to remove the decimal part of the number.
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```js
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assert(code.match(/Math.floor/g).length >= 1);
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```
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# --seed--
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## --after-user-code--
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```js
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(function(){return randomWholeNum();})();
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```
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## --seed-contents--
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```js
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function randomWholeNum() {
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return Math.random();
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}
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```
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# --solutions--
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```js
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function randomWholeNum() {
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return Math.floor(Math.random() * 10);
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}
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```
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