diff --git a/index.js b/index.js
index 8b13789..d4e2549 100644
--- a/index.js
+++ b/index.js
@@ -1 +1,124 @@
+const readline = require('readline');
+const add = require("./modules/add");
+const subtract = require("./modules/subtract");
+const multiply = require("./modules/multiply");
+const divide = require("./modules/divide");
+const assignVariable = require("./modules/assignVariable");
+const {lessThan, greaterThan, isEqual, isNotEqual} = require("./modules/boolean");
 
+const rl = readline.createInterface({
+    input: process.stdin,
+    output: process.stdout
+   });
+
+
+function prompt(){
+    rl.question('What would you like to calculate? ', (answer) => {
+        calculate(answer);
+        prompt();
+    })
+}
+prompt();
+
+function determineOperator(string){
+    let regex = /[\/\+\-\*\>\<\=\!]/g;
+    let opLocStart = string.search(regex)
+    let opLocBoolEnd = opLocStart+3;
+    let operation = string.charAt(opLocStart);
+    if(opLocStart === -1){
+        return false;
+    }
+    else if(operation == '=' || operation == '!'){
+        let boolOp = string.slice(opLocStart, opLocBoolEnd);
+        if(boolOp == '==='){
+            return ["===", opLocStart];
+        }
+        else if(boolOp == '!=='){
+            return ["!==", opLocStart];
+        }
+        else if (operation == '='){
+            return ['=', opLocStart];
+        }
+        else{
+            return false;
+        }
+    }
+    else if(operation.match(regex)){
+        return [operation, opLocStart];
+    }
+}
+
+function calculate(answer){
+    let expression = answer;
+    if (determineOperator(expression)){
+        let [operation, location] = determineOperator(expression);
+        if((operation == '===')||(operation == '!==')){
+            let charAfterOp = location + 3;
+            let num1Str = expression.slice(0, location).trim();
+            let num2Str = expression.slice(charAfterOp, expression.length).trim()
+            let num1 = Number(num1Str);
+            let num2 = Number(num2Str);
+            if(!num1 || !num2){
+                
+                console.log("please enter expression in the following format: ")
+                console.log("number operation number")
+            }
+            else if(operation == '==='){
+                isEqual(num1, num2);
+            }
+            else if(operation == '!=='){
+                isNotEqual(num1, num2);
+            }
+        }
+        
+        else{
+            let charAfterOp = location + 1;
+            let num1Str = expression.slice(0, location).trim();
+            let varName = num1Str;
+            let num2Str = expression.slice(charAfterOp, expression.length).trim()
+            let num1 = Number(num1Str);
+            let num2 = Number(num2Str);
+            if(operation == '='){
+                if (num2){
+                    assignVariable(varName, num2)
+                }
+                else {
+                    let string = num2Str.split(/"/)[1];
+                    assignVariable(varName, string);
+                }
+                
+            }
+            else if(!num1 || !num2){
+                console.log("please enter expression in the following format: ")
+                console.log("number operator number")
+            }
+            
+            else if (operation === '+'){
+                add(num1, num2)
+            }
+            else if(operation === '-'){
+                subtract(num1, num2);
+            }
+            else if(operation === '*'){
+                multiply(num1, num2);
+            }
+            else if(operation === '/'){
+                divide(num1, num2);
+            }
+            else if(operation === '<'){
+                lessThan(num1, num2);
+            }
+            else if(operation === '>'){
+                greaterThan(num1, num2);
+            }
+        }
+    }
+    else{
+        if(global[answer]){
+            console.log(global[answer]);
+        }
+        else{
+            console.log("please enter valid mathematical oprator");
+        }
+    }
+}
\ No newline at end of file
diff --git a/modules/add.js b/modules/add.js
new file mode 100644
index 0000000..d2d00d3
--- /dev/null
+++ b/modules/add.js
@@ -0,0 +1,4 @@
+function add (num1, num2){
+    console.log(num1+num2);
+}
+module.exports = add;
\ No newline at end of file
diff --git a/modules/assignVariable.js b/modules/assignVariable.js
new file mode 100644
index 0000000..96d4f98
--- /dev/null
+++ b/modules/assignVariable.js
@@ -0,0 +1,4 @@
+function assignVariable (varName, value){
+    global[varName] = value;
+}
+module.exports = assignVariable; 
\ No newline at end of file
diff --git a/modules/boolean.js b/modules/boolean.js
new file mode 100644
index 0000000..50b823d
--- /dev/null
+++ b/modules/boolean.js
@@ -0,0 +1,15 @@
+module.exports.lessThan = function lessThan(num1, num2){
+    console.log(num1 < num2);
+}
+
+module.exports.greaterThan = function greaterThan(num1, num2){
+    console.log(num1 > num2);
+}
+
+module.exports.isEqual = function isEqual(num1, num2){
+    console.log(num1 == num2);
+}
+
+module.exports.isNotEqual = function isEqual(num1, num2){
+    console.log(num1 != num2);
+}
diff --git a/modules/divide.js b/modules/divide.js
new file mode 100644
index 0000000..2b47ad6
--- /dev/null
+++ b/modules/divide.js
@@ -0,0 +1,4 @@
+function divide (num1, num2){
+    console.log(num1/num2);
+}
+module.exports = divide;
\ No newline at end of file
diff --git a/modules/multiply.js b/modules/multiply.js
new file mode 100644
index 0000000..aaf7908
--- /dev/null
+++ b/modules/multiply.js
@@ -0,0 +1,4 @@
+function multiply (num1, num2){
+    console.log(num1*num2);
+}
+module.exports = multiply;
\ No newline at end of file
diff --git a/modules/subtract.js b/modules/subtract.js
new file mode 100644
index 0000000..3013dd3
--- /dev/null
+++ b/modules/subtract.js
@@ -0,0 +1,4 @@
+function subtract (num1, num2){
+    console.log(num1-num2);
+}
+module.exports = subtract;
\ No newline at end of file