Java Program to Find Product of First and Last Digit of a Number

How to get the first digit of a number in java – Java Program to Find Product of First and Last Digit of a Number

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How to get the first digit of a number in java: In the previous article, we have seen Java Program to Find Sum of First and Last Digit of a Number

In this article we will see how we can find the product of first and last digit of a number using Java programming language.

Java Program to Find Product of First and Last Digit of a Number

Get first digit of int java: If a number is given then starting digit of the number is called as first and end digit of the number is called as last digit of number.

For example:

If the number is 89453 then first digit is 8 and last digit is 3.

So the product of first and last digit = 8*3 =24

Let’s see different ways

Method-1: Java Program to Find Product of First and Last Digit of a Number By Finding Only First Digit Inside While Loop and Last Digit Outside Loop (Static Input Value)

Approach:

  • Declare an integer variable say ‘number‘ and initialize a value.
  • Declare two integer variables firstDigit and lastDigit and initialize both to 0.
  • Find last digit by lastDigit=number%10
  • Inside while loop find last digit by rem=number%10 and then number=number/10 and continuing the while loop till number value becomes 0.
  • After loop completes ‘rem‘ has the first digit.
  • Then find the product of of firstDigit and lastDigit

Program:

public class Main 
{
   public static void main(String args[])
   {
      //a number declared
      int number = 63365;
      //storing the number value in a temporary variable say 'temp'
      int temp=number;
      //declaring two integer variable firstDigit and lastDigit 
      //and initializing both with value as 0
      int firstDigit=0;
      int lastDigit=0;
      
      //find last digit of number
      lastDigit=number%10;
      
      //countinue the loop till the number becomes 0
      //inside loop variable 'firstDigit' will give the first digit at the end of while loop
      while(number!=0)
      {
         int rem = number%10;
         firstDigit=rem;
         number= number/10;
      }
      System.out.println("Number is: "+temp);
      System.out.println("First digit of number: "+ firstDigit );
      System.out.println("Last digit of number: "+ lastDigit);
      System.out.println("Product of first and last digit of number: "+ (firstDigit*lastDigit));
   }
}
Output:

Number is: 63365
First digit of number: 6
Last digit of number: 5
Product of first and last digit of number: 30

Method-2: Java Program to Find Product of First and Last Digit of a Number By Finding Only First Digit Inside While Loop and Last Digit Outside Loop (User Input Value)

Approach:

  • Declare an integer variable say ‘number‘ and take the value of it as user input.
  • Declare two integer variables firstDigit and lastDigit and initialize both to 0.
  • Find last digit by lastDigit=number%10
  • Inside while loop find last digit by rem=number%10 and then number=number/10 and continuing the while loop till number value becomes 0.
  • After loop completes ‘rem‘ has the first digit.
  • Then find the product of firstDigit and lastDigit

Program:

import java.util.*;

public class Main 
{
   public static void main(String args[])
   {
      Scanner sc=new Scanner(System.in);
      
      //taking a number input from user
      System.out.println("Enter a number: ");
      int number = sc.nextInt();
      //storing the number value in a temporary variable say 'temp'
      int temp=number;
      //declaring two integer variable firstDigit and lastDigit 
      //and initializing both with value as 0
      int firstDigit=0;
      int lastDigit=0;
      
      //find last digit of number
      lastDigit=number%10;
      
      //countinue the loop till the number becomes 0
      //inside loop variable 'firstDigit' will give the first digit at the end of while loop
      while(number!=0)
      {
         int rem = number%10;
         firstDigit=rem;
         number= number/10;
      }
      System.out.println("Number is: "+temp);
      System.out.println("First digit of number: "+ firstDigit );
      System.out.println("Last digit of number: "+ lastDigit);
      System.out.println("Product of first and last digit of number: "+ (firstDigit*lastDigit));
   }
}
Output:

Enter a number: 
45678
Number is: 45678
First digit of number: 4
Last digit of number: 8
Product of first and last digit of number: 32

Method-3: Java Program to Find Product of First and Last Digit of a Number – Finding First Digit  By Dividing Number with power of 10 ^ (totalDigits-1) and Last Digit By Number%10

Approach:

  • Declare an integer variable say ‘number‘ and initialize a value.
  • Declare two integer variables firstDigit and lastDigit and initialize both to 0.
  • Find last digit by lastDigit=number%10
  • Find first digit by firstDigit=number/((int) Math.pow(10, total_digits-1))
  • Then find product of firstDigit and lastDigit

 Program:

import java.util.*;

public class Main 
{
   public static void main(String args[])
   {
      Scanner sc=new Scanner(System.in);
      
      //taking a number input from user
      System.out.println("Enter a number: ");
      int number = sc.nextInt();
      //storing the number value in a temporary variable say 'temp'
      int temp=number;
      //declaring two integer variable firstDigit and lastDigit 
      //and initializing both with value as 0
      int firstDigit=0;
      int lastDigit=0;
      //initializing totalDigits as 0
      int totalDigits=0;
      
      //find last digit of number
      lastDigit=number%10;
      
      //countinue the loop till the number becomes 0
      //temp holds the value of number
      while(temp!=0)
      {
         temp= temp/10;
         totalDigits++;
      }
      
      //find first digit of number
      firstDigit=number/((int) Math.pow(10, totalDigits-1));
      
      System.out.println("Number is: "+number);
      System.out.println("Total Digits: "+totalDigits);
      System.out.println("First digit of number: "+ firstDigit );
      System.out.println("Last digit of number: "+ lastDigit);
      System.out.println("Product of first and last digit of number: "+ (firstDigit*lastDigit));
   }
}
Output:

Enter a number: 
56478
Number is: 56478
Total Digits: 5
First digit of number: 5
Last digit of number: 8
Product of first and last digit of number: 13

Enhancing programming skills is very important no matter what language you have chosen. So, practice frequently with these simple java programs examples and excel in coding the complex logic.

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