In the previous article, we have discussed Java Program to Check Mersenne Number

In this article we are going to understand what Hamming number is and how we can check whether a number is Hamming or not in Java with examples.

## Program to Check Hamming Number

**Hamming numbers** are numbers whose prime factors are 2, 3 or 5 only.

Example :

- 9: Prime Factors= 3*3 Hamming number
- 20: Prime Factors= 2*2*5 Hamming number
- 14: Prime Factors= 2*7 Not Hamming number

In the above examples the number 9 and 20 are Hamming numbers as they have no other prime factors than 2, 3 or 5. However 14 is not a Hamming number.

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**Approach :**

- We ask the user to enter or declare a number and store it .
- We find all the prime factors of the number.
- If there is no other prime factor than 2,3 or 5 then the number is said to be Hamming number.

### Program:

import java.util.Scanner; public class HammingNumber { public static void main(String args[]) { //Taking the number as input from the user using scanner class Scanner scan = new Scanner(System.in); System.out.print("Enter a number : "); int num = scan.nextInt(); boolean flag = true; for(int i = 2; i<=num; i++) { // Only checks for numbers except 2,3 and 5 if(i!=2&&i!=3&&i!=5) // Checks if there are some other prime factors if(num%i==0&&isPrime(i)) { // Sets the flag to false if there are some other prime factors flag = false; break; } } if(flag) { System.out.println(num+" is a Hamming number"); } else { System.out.println(num+" is Not a Hamming number"); } } // Function that checks for prime static boolean isPrime(int num) { boolean flag = true; for(int i = 2; i<=num/2; i++) { if(num%i==0) { flag = false; break; } } return flag; } }

Output: Case-1 Enter a number : 20 20 is a Hamming number Case-2 Enter a number : 21 21 is a Hamming number

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