diff --git a/Calculator.java b/Calculator.java
new file mode 100644
index 0000000..b68eb7d
--- /dev/null
+++ b/Calculator.java
@@ -0,0 +1,48 @@
+import java.util.Scanner;
+
+public class Calculator {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        // Prompt user for numbers
+        System.out.print("Enter first number: ");
+        double num1 = scanner.nextDouble();
+
+        System.out.print("Enter second number: ");
+        double num2 = scanner.nextDouble();
+
+        // Prompt user for operation
+        System.out.print("Enter operation (+, -, *, /): ");
+        char operator = scanner.next().charAt(0);
+
+        double result;
+
+        // Perform operation based on operator
+        switch (operator) {
+            case '+':
+                result = num1 + num2;
+                System.out.println("Result: " + result);
+                break;
+            case '-':
+                result = num1 - num2;
+                System.out.println("Result: " + result);
+                break;
+            case '*':
+                result = num1 * num2;
+                System.out.println("Result: " + result);
+                break;
+            case '/':
+                if (num2 != 0) {
+                    result = num1 / num2;
+                    System.out.println("Result: " + result);
+                } else {
+                    System.out.println("Error: Division by zero");
+                }
+                break;
+            default:
+                System.out.println("Invalid operator");
+        }
+
+        scanner.close();
+    }
+}
diff --git a/NumberGuessingGame.java b/NumberGuessingGame.java
new file mode 100644
index 0000000..c9f1751
--- /dev/null
+++ b/NumberGuessingGame.java
@@ -0,0 +1,41 @@
+import java.util.Random;
+import java.util.Scanner;
+
+public class NumberGuessingGame {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        Random random = new Random();
+
+        int minNumber = 1;
+        int maxNumber = 100;
+        int targetNumber = random.nextInt(maxNumber - minNumber + 1) + minNumber;
+        int maxAttempts = 5;
+        int attempts = 0;
+        boolean guessedCorrectly = false;
+
+        System.out.println("Welcome to the Number Guessing Game!");
+        System.out.println("I've picked a number between " + minNumber + " and " + maxNumber + ". Can you guess it?");
+
+        while (attempts < maxAttempts) {
+            System.out.print("Enter your guess: ");
+            int guess = scanner.nextInt();
+            attempts++;
+
+            if (guess == targetNumber) {
+                System.out.println("Congratulations! You've guessed the correct number in " + attempts + " attempts!");
+                guessedCorrectly = true;
+                break;
+            } else if (guess < targetNumber) {
+                System.out.println("Too low! Try again.");
+            } else {
+                System.out.println("Too high! Try again.");
+            }
+        }
+
+        if (!guessedCorrectly) {
+            System.out.println("Sorry, you've used all your attempts. The correct number was: " + targetNumber);
+        }
+
+        scanner.close();
+    }
+}
diff --git a/TemperatureConverter.java b/TemperatureConverter.java
new file mode 100644
index 0000000..22460fd
--- /dev/null
+++ b/TemperatureConverter.java
@@ -0,0 +1,85 @@
+import java.util.Scanner;
+
+public class TemperatureConverter {
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        while (true) {
+            System.out.println("Temperature Converter");
+            System.out.println("1. Celsius to Fahrenheit");
+            System.out.println("2. Fahrenheit to Celsius");
+            System.out.println("3. Celsius to Kelvin");
+            System.out.println("4. Kelvin to Celsius");
+            System.out.println("5. Fahrenheit to Kelvin");
+            System.out.println("6. Kelvin to Fahrenheit");
+            System.out.println("7. Exit");
+            System.out.print("Enter your choice: ");
+
+            int choice = scanner.nextInt();
+            double temperature;
+
+            switch (choice) {
+                case 1:
+                    System.out.print("Enter temperature in Celsius: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Fahrenheit: " + celsiusToFahrenheit(temperature));
+                    break;
+                case 2:
+                    System.out.print("Enter temperature in Fahrenheit: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Celsius: " + fahrenheitToCelsius(temperature));
+                    break;
+                case 3:
+                    System.out.print("Enter temperature in Celsius: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Kelvin: " + celsiusToKelvin(temperature));
+                    break;
+                case 4:
+                    System.out.print("Enter temperature in Kelvin: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Celsius: " + kelvinToCelsius(temperature));
+                    break;
+                case 5:
+                    System.out.print("Enter temperature in Fahrenheit: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Kelvin: " + fahrenheitToKelvin(temperature));
+                    break;
+                case 6:
+                    System.out.print("Enter temperature in Kelvin: ");
+                    temperature = scanner.nextDouble();
+                    System.out.println("Temperature in Fahrenheit: " + kelvinToFahrenheit(temperature));
+                    break;
+                case 7:
+                    System.out.println("Exiting...");
+                    scanner.close();
+                    System.exit(0);
+                default:
+                    System.out.println("Invalid choice");
+            }
+        }
+    }
+
+    public static double celsiusToFahrenheit(double celsius) {
+        return (celsius * 9 / 5) + 32;
+    }
+
+    public static double fahrenheitToCelsius(double fahrenheit) {
+        return (fahrenheit - 32) * 5 / 9;
+    }
+
+    public static double celsiusToKelvin(double celsius) {
+        return celsius + 273.15;
+    }
+
+    public static double kelvinToCelsius(double kelvin) {
+        return kelvin - 273.15;
+    }
+
+    public static double fahrenheitToKelvin(double fahrenheit) {
+        return (fahrenheit - 32) * 5 / 9 + 273.15;
+    }
+
+    public static double kelvinToFahrenheit(double kelvin) {
+        return (kelvin - 273.15) * 9 / 5 + 32;
+    }
+}
diff --git a/ToDoList.java b/ToDoList.java
new file mode 100644
index 0000000..2295978
--- /dev/null
+++ b/ToDoList.java
@@ -0,0 +1,113 @@
+import java.util.ArrayList;
+import java.util.Scanner;
+
+class Task {
+    private String description;
+    private boolean completed;
+
+    public Task(String description) {
+        this.description = description;
+        this.completed = false;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public boolean isCompleted() {
+        return completed;
+    }
+
+    public void markAsCompleted() {
+        this.completed = true;
+    }
+
+    @Override
+    public String toString() {
+        return (completed ? "[X] " : "[ ] ") + description;
+    }
+}
+
+public class ToDoList {
+    private ArrayList<Task> tasks;
+
+    public ToDoList() {
+        this.tasks = new ArrayList<>();
+    }
+
+    public void addTask(String description) {
+        tasks.add(new Task(description));
+    }
+
+    public void deleteTask(int index) {
+        if (index >= 0 && index < tasks.size()) {
+            tasks.remove(index);
+        } else {
+            System.out.println("Invalid index");
+        }
+    }
+
+    public void markTaskAsCompleted(int index) {
+        if (index >= 0 && index < tasks.size()) {
+            tasks.get(index).markAsCompleted();
+        } else {
+            System.out.println("Invalid index");
+        }
+    }
+
+    public void displayTasks() {
+        if (tasks.isEmpty()) {
+            System.out.println("No tasks");
+        } else {
+            for (int i = 0; i < tasks.size(); i++) {
+                System.out.println((i + 1) + ". " + tasks.get(i));
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+        ToDoList todoList = new ToDoList();
+
+        while (true) {
+            System.out.println("\n---- ToDo List Menu ----");
+            System.out.println("1. Add Task");
+            System.out.println("2. Delete Task");
+            System.out.println("3. Mark Task as Completed");
+            System.out.println("4. Display Tasks");
+            System.out.println("5. Exit");
+            System.out.print("Enter your choice: ");
+
+            int choice = scanner.nextInt();
+            scanner.nextLine();  // Consume newline character
+
+            switch (choice) {
+                case 1:
+                    System.out.print("Enter task description: ");
+                    String description = scanner.nextLine();
+                    todoList.addTask(description);
+                    break;
+                case 2:
+                    System.out.print("Enter index of task to delete: ");
+                    int deleteIndex = scanner.nextInt();
+                    todoList.deleteTask(deleteIndex - 1);
+                    break;
+                case 3:
+                    System.out.print("Enter index of task to mark as completed: ");
+                    int completeIndex = scanner.nextInt();
+                    todoList.markTaskAsCompleted(completeIndex - 1);
+                    break;
+                case 4:
+                    System.out.println("\n---- Tasks ----");
+                    todoList.displayTasks();
+                    break;
+                case 5:
+                    System.out.println("Exiting...");
+                    scanner.close();
+                    System.exit(0);
+                default:
+                    System.out.println("Invalid choice");
+            }
+        }
+    }
+}