Programming Examples

Java program to input an integer and check whether it is Harshad or Niven number or not


Write a Program in Java to input a number and check whether it is a Harshad Number or Niven Number or not.

Harshad Number : In recreational mathematics, a Harshad number (or Niven number), is an integer (in base 10) that is divisible by the sum of its digits.

Let’s understand the concept of Harshad Number through the following example:

  • The number 18 is a Harshad number in base 10, because the sum of the digits 1 and 8 is 9 (1 + 8 = 9), and 18 is divisible by 9 (since 18 % 9 = 0)
  • The number 1729 is a Harshad number in base 10, because the sum of the digits 1 ,7, 2 and 9 is 19 (1 + 7 + 2 + 9 = 19), and 1729 is divisible by 19 (1729 = 19 * 91)
  • The number 19 is not a Harshad number in base 10, because the sum of the digits 1 and 9 is 10 (1 + 9 = 10), and 19 is not divisible by 10 (since 19 % 10 = 9)

The first few Harshad numbers in base 10 are:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 18, 20, 21, 24, 27, 30, 36, 40, 42, 45, 48, 50, 54, 60, 63, 70, 72, 80, 81, 84, 90, 100, 102, 108, 110, 111, 112, 114, 117, 120, 126, 132, 133, 135, 140, 144, 150, 152, 153, 156, 162, 171, 180, 190, 192, 195, 198, 200 etc.

Sample:

Enter a number : 195

195 is a Harshad Number.

Enter a number : 194

194 is not a Harshad Number.

Enter a number : 190

190 is a Harshad Number.

Enter a number : 111

111 is a Harshad Number.

Solution

import java.util.*;
class Harshad
{
	public static void main(String arr[])
	{
		Scanner sc=new Scanner(System.in);
		int i,d,a,s=0;
		System.out.println("Enter an integer:");
		a=sc.nextInt();
		for(i=a;i>0;i=i/10)
		{
			d=i%10;
			s+=d;
		}
		if(a%s==0)
			System.out.println("Harshad Number");
		else
			System.out.println("Not a Harshad Number");
	}
}
Output

Enter a number : 195

195 is a Harshad Number.

Enter a number : 194

194 is not a Harshad Number.

Enter a number : 190

190 is a Harshad Number.

Enter a number : 111

111 is a Harshad Number.

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