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### Sum All Primes (Main Thread)

Here is the interview question prompt, presented for reference.

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)`

You can see the full challenge with visuals at this link.

Challenges • Asked 11 months ago by Anonymous Jake from AlgoDaily Commented on Jul 21, 2020:

This is the main discussion thread generated for Sum All Primes. Anonymous Commented on Jul 21, 2020:

sumOfAllPrimes(15) should return 65, as the question asks for all prime numbers smaller than or equal to n correct? Anonymous Commented on Jul 21, 2020:

Never mind I misread the question Giovani Commented on May 04, 2021:

This solution is O(n log n), right? But O(1) in space

``````function sumOfPrimes(n) {
let total = 0;

for(let i = 2; i <= n; i++) {
if(isPrime(i)) {
total += i;
}
}

return total;
}

function isPrime(n) {
for(i = 2; i <= Math.sqrt(n); i++) {
if(n % i === 0) return false;
}

return true;
}
``````