JAVA. B03 - Multiply even digits Write a program that will ask the user for a nu

Question

JAVA.

B03 - Multiply even digits Write a program that will ask the user for a number, and then recursively computes the multiplication of every even number that is less than the given number. That is, if the user enters 13, your program would recursively compute 12*10*8*6*4*2.

Hint: Define the following method:

public static long computeMultiplication(int n)

Note: Validate the user input to make sure the entered number is a positive integer. Otherwise, keep asking the user for a number until the input is valid.

Explanation / Answer

import java.util.Scanner;

/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/

/**
*
* @author Vamsi
*/
public class Multiplication {
  
  
  
public static long computeMultiplication(int n)
{
if(n==0)
return 1;
if(n%2==0)//if n is even...then multiplying
return computeMultiplication(n-1)*n;//recursive calls
return computeMultiplication(n-1);
}

public static void main(String argv[])
{
int n ;
//to read input...
Scanner sc = new Scanner(System.in);
  
while(true)//runs upto positive value is entered
{
System.out.println("Enter positive number :");
n = sc.nextInt();//reading number
  
if(n>0)//validating input
break;
  

}
long r = computeMultiplication(n-1);
System.out.println("Result : "+r);
}
}

output:

run:
Enter positive number :
8
Result : 48
BUILD SUCCESSFUL (total time: 2 seconds)

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