Java Program for Even/Odd and Sum of N Natural Numbers

Check if a Number is Even or Odd in Java

Given an integer input, the objective is to determine whether a number is even or odd using Java programming.

An even number is completely divisible by 2, whereas an odd number leaves a remainder of 1 when divided by 2.

Example:

Input: Num = -5

Output: The number is Negative

Methods to Check Even or Odd

Method 1: Using Brute Force
Method 2: Using Nested if-else Statements
Method 3: Using the Ternary Operator

Sum of First N Natural Numbers (Java)

Natural numbers are a sequence of positive numbers starting from 1. The sum of the first N natural numbers can be calculated using different methods.

Method 1: Using for Loop (Java)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Kindly Insert an Integer Variable: ");
        int n = scanner.nextInt();
        int sum = 0;
        for (int i = 1; i <= n; i++) {
            sum += i;
        }
        System.out.println("Sum of Natural Numbers = " + sum);
        scanner.close();
    }
}

Output:

Kindly Insert an Integer Variable: 3 
Sum of Natural Numbers = 6

Method 2: Using Formula (Java)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Kindly Insert an Integer Variable: ");
        int n = scanner.nextInt();
        int sum = n * (n + 1) / 2;
        System.out.println("Sum of Natural Numbers = " + sum);
        scanner.close();
    }
}

Output:

Kindly Insert an Integer Variable: 3 
Sum of Natural Numbers = 6

Method 3: Using Recursion (Java)

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Kindly Insert an Integer Variable: ");
        int n = scanner.nextInt();
        System.out.println("Sum of Natural Numbers = " + getSum(n));
        scanner.close();
    }
    static int getSum(int n) {
        if (n == 0)
            return 0;
        return n + getSum(n - 1);
    }
}

Output:

Kindly Insert an Integer Variable: 3 
Sum of Natural Numbers = 6