Tag: java loop program

The following program takes the value for n that is the max limit of n from the user. The program starts checking for odd numbers between this range 1 to n and it displays all the odd numbers lying within that range.

Before we start, click on the links below to have a proper working idea of for loop and if statement that this program uses.

• for loop
• if statement

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Program to display the Odd Numbers within the range in Java

//display the odd number in java

 import java.util.*;

 public class DisplayOddNumbers
 {
    public static void main(String args[]) 
    {
  int n;
  Scanner sc=new Scanner(System.in);
  
  System.out.print("Enter the number: ");
    n=sc.nextInt();
    
  System.out.print("Odd Numbers between 1 to "+n+" are: ");
  
    for (int i = 1; i <= n; i++) 
    {
      // if the number is not divisible by 2 then it is even
      if (i % 2 != 0) 
      {
        System.out.print(i + " ");
      }
    }
  }
 }

Output:

Enter the number: 10
Odd Numbers between 1 to 10 are: 1 3 5 7 9

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In this example, we will calculate the factorial of a number taking the value from the user. You may also learn to find Factorial of a Number in Java Using recursion.

Before we begin, you should have the knowledge of the following:

• Java Data-Types
• Java Operators
• Java for loop

Factorial of n number: Factorial of n number is the product of all the positive descending integers and is denoted by n!.

Example:

factorial of n (n!) = n * (n-1) * (n-2) * (n-3)….1
factorial of 5 (n!) = 5 * 4 * 3 * 2 * 1
NOTE: Factorial of 0 (0!) = 1

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Java Program to Find a Factorial of a Number Using for loop.

 //find the factorial of a number in java

 import java.util.Scanner;

 public class FactorialOfANumber
 {
  public static void main(String args[])
  {
    int fact=1;
    Scanner scanner = new Scanner(System.in);

    System.out.print("Enter the number: ");
    int num = scanner.nextInt();

    for(int i=1;i<=num;i++)
    {
     fact = fact * i;
    }
    System.out.println("Factorial of entered number is: "+fact);
  }

 }

Output:

Enter the number: 5
Factorial of entered number is: 120

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It is the Basic Java Program to find the sum of N natural numbers. The program below uses the While loop, if you want to learn about the while loop click below.

• While loop in Java

Example: If you want to find the sum of 5 natural numbers, the process will be executed in this manner:
1 + 2 + 3 + 4 + 5
The result will be: 15

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Java Program to Find the Sum of Natural Numbers using While Loop

//Sum of Natural numbers in java
  
public class SumNaturalNumbers 
{
  public static void main(String[] args) 
   {

   int n = 100, count = 1, sum = 0;

   while(count <= n)
   {
       sum = sum + count;
       count++;
   }

   System.out.println("Sum: "+sum);
   }
}

Output:

Sum: 5050

In the above program, n is already defined in the program but if you wish to take the input of n from the user, just use the scanner class.

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The following Java Program uses the Multiplication and Modulus Operator to reverse the number entered by the User. Something like this,

If the entered Number is 1234567, then the final result will display 7654321.

If you do not know about the Operator in Java, click the link below.

• Java Operator

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Example: Java Program to Reverse the Number using while loop

//reverse a number in java

 import java.util.Scanner;

 public class ReverseNumberJava
 {
   public static void main(String args[])
   {
     int n, rev = 0;

     Scanner in = new Scanner(System.in);

     System.out.print("Enter an integer to reverse: ");
     n = in .nextInt();

     while (n != 0)
     {
       rev = rev * 10;
       rev = rev + n % 10;
       n = n / 10;
     }

     System.out.println("Reverse of the entered interger is " + rev);
   }
 }

Output of reversing a number:

Enter an integer to reverse: 1234567
Reverse of the entered interger is 7654321

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