25 lines
581 B
Markdown
25 lines
581 B
Markdown
---
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title: Number is prime
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tags: math,algorithm
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cover: thread
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firstSeen: 2017-12-19T22:35:56+02:00
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lastUpdated: 2021-01-12T19:36:36+02:00
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---
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Checks if the provided integer is a prime number.
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- Check numbers from `2` to the square root of the given number.
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- Return `false` if any of them divides the given number, else return `true`, unless the number is less than `2`.
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```js
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const isPrime = num => {
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const boundary = Math.floor(Math.sqrt(num));
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for (let i = 2; i <= boundary; i++) if (num % i === 0) return false;
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return num >= 2;
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};
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```
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```js
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isPrime(11); // true
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```
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