diff --git a/app.js b/app.js
index 981fc0d..60846f3 100644
--- a/app.js
+++ b/app.js
@@ -2,3 +2,174 @@ console.log("Hello World!\n==========\n");
 
 // Exercise 1 Section
 console.log("EXERCISE 1:\n==========\n");
+
+class Person {
+    constructor(name,pets,residence,hobbies =[]){
+    this.name=name;
+    this.pets=pets;
+    this.residence=residence;
+    this.hobbies=hobbies;
+
+}
+addHobby(hobby){
+     this.hobbies.push(hobby);
+}
+greet(name){
+    console.log(`hello fellow ${name}!`);
+}
+removeHobby(remHob){
+    // function filterHobby(hobby)
+    // { if (hobby === remHob )
+    //     return false;
+    // }else { 
+    //     return true;
+    // }
+   this.hobbies= this.hobbies.filter((hob)=>hob != remHob );
+}
+   
+}
+// let sharr= new Person("aman",1,"ajf",["all","afjk"])
+// console.log(sharr);
+let aman =new Person("aman",2,"slater avenue",["sleep","coding","repeat"]);
+aman.removeHobby("repeat");
+aman.addHobby("soccor");
+console.log(aman);
+// aman.greet();
+
+console.log("EXERCISE 2:\n==========\n");
+class Coder extends Person{
+    constructor(name,pets,residence,hobbies=[]){
+        super (name,pets,residence,hobbies);
+        this.occupation="Full Stack web Developer"
+    }
+    greet(name){
+        console.log(`hello  ${name}! how are you`);
+    }
+}
+ let bob= new Coder("bob",23,"hills",["gym","reading","love"]);
+ console.log(bob);
+ bob.greet(aman.name);
+ aman.greet(bob.name);
+                                                 
+
+
+// console.log("EXERCISE 3:\n==========\n");
+
+
+console.log("EXERCISE 4:\n==========\n");
+
+class Calculator {
+    result = 0;
+    a;
+    b;
+    op;
+    shouldContinue = false;
+  
+    start() {
+      do {
+        this.a = this.getInput("First Number", true);
+        this.b = this.getInput(
+          "Second Number (give no number to use previous result)",
+          true
+        );
+        this.op = this.getInput(
+          "Operation: ('+' for addition, '-' for subtraction, '*' for multiplication, '/' for division)",
+          false
+        );
+  
+        if (isNaN(this.b)) {
+          this.b = undefined;
+        }
+  
+        switch (true) {
+          case isNaN(this.a):
+            alert("Invalid input");
+            break;
+          case this.op == "+":
+            this.add(this.a, this.b);
+            this.displayResult();
+            break;
+          case this.op == "-":
+            this.subtract(this.a, this.b);
+            this.displayResult();
+            break;
+          case this.op == "*":
+            this.multiply(this.a, this.b);
+            this.displayResult();
+            break;
+          case this.op == "/":
+            this.divide(this.a, this.b);
+            this.displayResult();
+            break;
+          default:
+            alert("Invalid operation");
+        }
+  
+        let continueInput = this.getInput("Again? (type 'yes')", false);
+  
+        this.shouldContinue = continueInput == "yes";
+      } while (this.shouldContinue);
+    }
+  
+    add(a, b) {
+      if (b === undefined) {
+        this.result += a;
+      } else {
+        this.result = a + b;
+      }
+  
+      return this.result;
+    }
+  
+    subtract(a, b) {
+      if (b === undefined) {
+        this.result -= a;
+      } else {
+        this.result = a - b;
+      }
+  
+      return this.result;
+    }
+  
+    multiply(a, b) {
+      if (b === undefined) {
+        this.result *= a;
+      } else {
+        this.result = a * b;
+      }
+  
+      return this.result;
+    }
+  
+    divide(a, b) {
+      if (b === undefined) {
+        this.result /= a;
+      } else {
+        this.result = a / b;
+      }
+  
+      return this.result;
+    }
+  
+    clear() {
+      this.result = 0;
+    }
+  
+    displayResult() {
+      alert(this.result);
+    }
+  
+    getInput(msg, isNumber) {
+      let input = prompt(msg);
+  
+      if (isNumber) {
+        return parseFloat(input);
+      }
+  
+      return input;
+    }
+  }
+  
+  let calculator = new Calculator();
+  
+  calculator.start();
\ No newline at end of file