# How to check if a number is Hoax or not in Java

**What is a Hoax Number?**

A Hoax number is defined as a composite number, whose sum of digits is equal to the sum of digits of its distinct prime factors.

Note: 1 is not considered a prime number, hence it is not included in the sum of digits of distinct prime numbers.

For example:

Input: 22 The sum of digits: 2+2=4 Prime factors: 2,11 The sum of digits of its distinct prime factors: 2+1+1=4 Output: it is a Hoax number

Input: 15 The sum of digits: 1+5=6 Prime factors: 3,5 The sum of digits of its distinct prime factors: 3+5=8 Output: it is not a Hoax number

Input: 84 The sum of digits: 8+4=12 Prime factors: 2,3,7,2 Distinct prime factors: 2,3,7 The sum of digits of its distinct prime factors: 2+3+7=12 Output: it is a Hoax number

Steps to find if Number is Hoax or not:

- Enter the number.
- Obtain prime factors of a number.
- Find the sum of digits of distinct prime factors.
- Find the sum of digits of the number.
- Check if the sum obtained from steps 3 and 4 are equal or not.
- If sums are equal then the number is a Hoax number.

## How to check if a number is a Hoax or not in Java

Below is our given Java code that is checking a number if it is Hoax or not:

import java.util.*; public class pfactors{ public static void main(String[] args){ int num,num1,sum=0,n,i,sum2=0,digit; Scanner sc=new Scanner(System.in); //enter the number n=sc.nextInt(); int temp=n; List<Integer> value = new ArrayList<Integer>(); List<Integer> value1 = new ArrayList<Integer>(); //check till number is greater than 1 while(n>1){ //find prime factors for a given number //smallest prime number is 2 for(i=2;i<=n;i++){ if(n%i==0){ n=n/i; value.add(i); //add in the arraylist } } } //to check duplicates in the arraylist for(int x: value){ if(!value1.contains(x)){ value1.add(x); //add distinct values from arraylist in another arraylist } } //find sum of digits in arraylist for(int j=0;j<value1.size();j++){ num=value1.get(j); while(num>0){ num1=num%10; if(num1!=0){ sum=sum+num1; } num=num/10; } } System.out.println("sum of digits of prime factors: "+sum); //find sum of digits of the number entered while(temp>0){ digit=temp%10; sum2=sum2+digit; temp=temp/10; } System.out.println("sum of digits of number entered: "+sum2); //check if number is hoax or not if(sum==sum2){ System.out.println("number is hoax"); } else{ System.out.println("number is not hoax"); } } }

Output:

84 sum of digits of prime factors: 12 sum of digits of number entered: 12 number is hoax

15 sum of digits of prime factors: 8 sum of digits of number entered: 6 number is not hoax

#### Explanation of this program:

- Enter the number, n to be checked.
- If n is greater than 1, Iterate the loop. The prime number starts from 2, so initially, start the loop from 2, i.e. i=2.
- if n%i=0, add i in the ArrayList and return n=n/i for further iterations.
- To check distinct prime factors, check if the ArrayList contains any duplicate elements and add distinct elements in another ArrayList.
- Now, to find the sum of digits in ArrayList, iterate the loop till the size of ArrayList.
- Find the sum of each digit present in the array.
- Print the sum of digits of prime factors.
- Now, find the sum of digits of the number entered, and print.
- Finally, check the sums obtained from steps 7 and 8, if they are equal then the number is a Hoax else It is not a Hoax number.

This is how we can check if the number is a Hoax or not. I hope you find this tutorial useful.

Keep it up ishikaa , even I want to learn Coding