Advanced freeCodeCamp • intermediate-algorithm-scripting

Sum All Primes

Challenge Overview

A <dfn>prime number</dfn> is a whole number greater than 1 with exactly two divisors: 1 and itself. For example, 2 is a prime number because it is only divisible by 1 and 2. In contrast, 4 is not p...

A prime number is a whole number greater than 1 with exactly two divisors: 1 and itself. For example, 2 is a prime number because it is only divisible by 1 and 2. In contrast, 4 is not prime since it is divisible by 1, 2 and 4.

Rewrite sumPrimes so it returns the sum of all prime numbers that are less than or equal to num.

💡 View Solution

function sumPrimes(num) {
  function isPrime(n) {
    for (let i = 2; i <= Math.sqrt(n); i++) if (n % i === 0) return false;
    return n > 1;
  }
  let sum = 0;
  for (let i = 2; i <= num; i++) if (isPrime(i)) sum += i;
  return sum;
}