Project Euler | Problem 4 | Largest palindrome product

Problem Description :

A palindromic number reads the same both ways. The largest palindrome made from the product of two 2-digit numbers is 9009 = 91 × 99.
Find the largest palindrome made from the product of two 3-digit numbers?

Concept :

A palindromic number or numeral palindrome is a number that remains the same when its digits are reversed. For example 99 is a palindrome but 89 is not.

Java Program :

package com.javamultiplex.projecteuler;

 * @author Rohit Agarwal
 * @category Project Euler Problems
 * @problem Largest palindrome product
public class Problem4 {

 public static void main(String[] args) {

  int maxThreeDigit = 999;
  int minThreeDigit = 100;
  int multInteger = 0;
  // lowest multiple of 2 three digit numbers
  int max = 100 * 100;
  for (int i = maxThreeDigit; i >= minThreeDigit; i--) {
   for (int j = i; j >= minThreeDigit; j--) {
    multInteger = i * j;

    // Checking multiplication is palindrome or not
    if (isPalindrome(multInteger)) {
     if (multInteger > max) {
      max = multInteger;
  System.out.println("Largest palindrom made from the product of two 3-digit numbers is: "
      + max);

 private static boolean isPalindrome(int multInteger) {

  boolean result = false;
  String multString = null;
  StringBuffer multStringBuffer = null;
  // Converting Integer to String
  multString = String.valueOf(multInteger);
   * Converting String to StringBuffer, We want to reverse the string
   * thats why we have to use StringBuffer.
  multStringBuffer = new StringBuffer(multString);
  if (multString.equals(multStringBuffer.reverse().toString())) {
   result = true;
  } else {
   result = false;
  return result;


Output :

Output of Project Euler Problem 4 - Largest Palindrome Product in Java
Output - Project Euler Problem 4

References :

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Tags : Project Euler Problem 4, Solution in Java, Mathematics problems, Largest palindrome product, if else statement, for loop, String, StringBuffer.

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Project Euler | Problem 4 | Largest palindrome product Project Euler | Problem 4 | Largest palindrome product Reviewed by Rohit Agarwal on 12/15/2016 Rating: 5

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