Good morning! Here's our prompt for today.

You're given a number n. Can you write a method sumOfAllPrimes that finds all prime numbers smaller than or equal to n, and returns a sum of them?

For example, we're given the number 15. All prime numbers smaller than 15 are:

2, 3, 5, 7, 11, 13

They sum up to 41, so sumOfAllPrimes(15) would return 41.

Constraints

• n will always be a non zero positive integer <= 100000
• Expected time complexity : O(nlogn)
• Expected space complexity : O(n)

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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var assert = require('assert');

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function sumOfPrimes(n) {

  // fill this in

  return n;

}

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console.log(sumOfPrimes(7));

console.log(sumOfPrimes(15));

​

try {

  assert.deepEqual(2, sumOfPrimes(2), 'sumOfPrimes(2) should equal 2');

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  console.log('PASSED: ' + '`sumOfPrimes(2)` should equal `2`');

} catch (err) {

  console.log(err);

}

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try {

  assert.deepEqual(129, sumOfPrimes(30), 'sumOfPrimes(30) should equal 129');

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  console.log('PASSED: ' + '`sumOfPrimes(30)` should equal `129`');

} catch (err) {

  console.log(err);

}

​

try {

  assert.deepEqual(381, sumOfPrimes(55), 'sumOfPrimes(55) should equal 381');

​

Here's our guided, illustrated walk-through.

How do I use this guide?