Euler Problem #3

by gcarino

HTML

<h1>Project Euler Problem 3:</h1>
<h4>The prime factors of 13195 are 5, 7, 13 and 29.

What is the largest prime factor of the number 600851475143 ?</h4>

CSS

h1{
    text-decoration:underline;
    text-align:center;
    color:grey;
}

JavaScript

console.log(Math.sqrt(600851475143)); //775146.0992245268 

var primes = [];

for(var i=1; i<Math.sqrt(600851475143); i++){
    if(600851475143%i === 0){
        if(isPrime(i)){
            primes.push(i);
        }
    }
}

function isPrime(n){
    if(n===2 || n ===3){
        return true;
    } else if(i%2 === 0){
        return false;
    }
    var max = Math.sqrt(n);
    for(var i=5 ; i<max; i+=2){
        if(n%i === 0){
            return false;
        }
    }
    return true;
}

var largest = primes[primes.length-1];    

var para = document.createElement("p");
var txt = document.createTextNode("Largest Prime factor: " + largest);
para.appendChild(txt);
document.body.appendChild(para);