freeCodeCamp/curriculum/challenges/en/08-coding-interview-prep/project-euler/problem-3-largest-prime-factor.en.md

id, challengeType, title

id	challengeType	title
5900f36f1000cf542c50fe82	5	Problem 3: Largest prime factor

Description

The prime factors of 13195 are 5, 7, 13 and 29. What is the largest prime factor of the given number?

Instructions

Tests

- text: <code>largestPrimeFactor(2)</code> should return 2.
  testString: 'assert.strictEqual(largestPrimeFactor(2), 2, ''<code>largestPrimeFactor(2)</code> should return 2.'');'
- text: <code>largestPrimeFactor(3)</code> should return 3.
  testString: 'assert.strictEqual(largestPrimeFactor(3), 3, ''<code>largestPrimeFactor(3)</code> should return 3.'');'
- text: <code>largestPrimeFactor(5)</code> should return 5.
  testString: 'assert.strictEqual(largestPrimeFactor(5), 5, ''<code>largestPrimeFactor(5)</code> should return 5.'');'
- text: <code>largestPrimeFactor(7)</code> should return 7.
  testString: 'assert.strictEqual(largestPrimeFactor(7), 7, ''<code>largestPrimeFactor(7)</code> should return 7.'');'
- text: <code>largestPrimeFactor(13195)</code> should return 29.
  testString: 'assert.strictEqual(largestPrimeFactor(13195), 29, ''<code>largestPrimeFactor(13195)</code> should return 29.'');'
- text: <code>largestPrimeFactor(600851475143)</code> should return 6857.
  testString: 'assert.strictEqual(largestPrimeFactor(600851475143), 6857, ''<code>largestPrimeFactor(600851475143)</code> should return 6857.'');'

Challenge Seed

function largestPrimeFactor(number) {
  // Good luck!
  return true;
}

largestPrimeFactor(13195);

Solution

const largestPrimeFactor = (number)=>{
  let largestFactor = number;
  for(let i = 2;i<largestFactor;i++){
  if(!(largestFactor%i)){
    largestFactor = largestFactor/i;
    largestPrimeFactor(largestFactor);
  }
  }
  return largestFactor;
}