Question 53128 in Javascript Question posted in
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How to find prime numbers between 0 – 100 in javascript without using built in funcitions ? both count of primes numbers and numbers itself

I am trying to find the prime numbers from 1-n (say n=100). Without using built in functions. I have thought about it, and I am not sure how to find them. I tried using two for loops and a count variable to know the count of prime numbers between 1-n. And I also want print these numbers on console.


function countPrimes(num){
  let count=0
  let primeCount=0;
  let i,j
  for(j=2;j<=num;j++)
  {
  for( i=2;i<=j;i++)
  {
    if(j%i==0)
    count++
  }

  if(count==2){
    primeCount++;
  }
  count=0



  }
  return primeCount;
}

console.log(countPrimes(100));

I try to run the above code but getting nothing in the console.

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2

Answers


  1. 0

    Try to use this code:

    function countPrimes(num){
  let count = 0;
  for(let i = 2; i <= num; i++){
    let isPrime = true;
    for(let j = 2; j < i; j++){
      if(i % j == 0){
        isPrime = false;
        break;
      }
    }
    if(isPrime){
      count++;
      console.log(i);
    }
  }
  return count;
}

console.log(countPrimes(100));
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  2. 0

    Every number is divided by 1 so we will start i loop from 2

    function countPrimes(num){
  let count = 0;
  for(let i = 2; i <= num; i++){
    let prime = true;
    for(let j = 2; j < i; j++){
      if(i % j == 0){
        prime = false;
        break;
      }
    }
    if(prime){
      count++;
      console.log("Prime number", i);
    }
  }
  return count;
}

console.log("total Prime numbers",countPrimes(100));
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