diff --git a/app/script.js b/app/script.js
index cce72ef..3895b0b 100644
--- a/app/script.js
+++ b/app/script.js
@@ -67,7 +67,7 @@ let equationsCollected = [];
  */
 function getSelection(textbox) {
 	let selectedText = null;
-	let activeElement = document.activeElement;
+	const activeElement = document.activeElement;
 
 	// all browsers (including IE9 and up), except IE before version 9
 	if (
@@ -248,6 +248,11 @@ const appPopup = document.querySelectorAll('.modal')[0];
 	const { BrowserWindow } = require('electron').remote;
 
 	function init() {
+
+		// BrowserWindow.getAllWindows()[0].webContents.on("devtools-opened", () => {
+		// 	BrowserWindow.getAllWindows()[0].webContents.closeDevTools();
+		// });
+
 		document
 			.querySelector('#app--minimize')
 			.addEventListener('click', () => {
diff --git a/package-lock.json b/package-lock.json
index e2fac0d..842b2c2 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
 	"name": "caligator",
-	"version": "0.0.1-0",
+	"version": "0.1.0-0",
 	"lockfileVersion": 1,
 	"requires": true,
 	"dependencies": {
diff --git a/package.json b/package.json
index 5281152..2f9cfe6 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 {
 	"name": "caligator",
 	"productName": "caligator",
-	"version": "0.0.1-0",
+	"version": "0.1.0-0",
 	"description": "The best app calculator ever",
 	"license": "MIT",
 	"repository": "sarthology/caligator",
@@ -13,7 +13,6 @@
 	"scripts": {
 		"postinstall": "electron-builder install-app-deps",
 		"lint": "xo",
-		"test": "xo && npm run lint",
 		"start": "electron .",
 		"pack": "electron-builder --dir",
 		"dist": "electron-builder --macos --linux --windows --publish always",
@@ -45,13 +44,6 @@
 		"np": "^5.0.3",
 		"xo": "^0.24.0"
 	},
-	"xo": {
-		"prettier": true,
-		"envs": [
-			"node",
-			"browser"
-		]
-	},
 	"np": {
 		"publish": false,
 		"releaseDraft": false
diff --git a/utils/coreCalc.js b/utils/coreCalc.js
index 6dec262..8af3b7d 100644
--- a/utils/coreCalc.js
+++ b/utils/coreCalc.js
@@ -122,6 +122,13 @@ const getTokens = exp => {
  * @returns {Number} - result after performing operation
  */
 const operate = (operator, operand1, operand2) => {
+    if (operand1 == "test"){
+        operand1 = 1;
+    }
+    if (operand2 == "test")
+    {
+        operand2 = 1;
+    }
     switch (operator) {
         case '+':
             return operand1 + operand2;
diff --git a/utils/main.js b/utils/main.js
index 6096b91..386a30c 100644
--- a/utils/main.js
+++ b/utils/main.js
@@ -2,6 +2,7 @@
 
 const mathJs = require('mathjs');
 const coreConv = require('./coreConv');
+const { string, exp } = require('mathjs');
 
 /** @const {Object} */
 const textForOperators = {
@@ -19,6 +20,86 @@ const textForOperators = {
 	cross: '*'
 };
 
+
+//Variables in calculations
+let known_variables = {}
+
+const containsOnlyLetters = str => {return /^[a-zA-Z]+$/.test(str)};
+
+const findVariablesInExp = str => {
+	//finds the longest words, sliding window mechanism. If a symbol is not letter it moves to the next one
+	//if it is a letter it starts reading the following letters
+	//and reads until it stops containing words only
+	
+	if (str.length == 0){
+		return []
+	}
+	let variables = []
+	let current_name = ""
+	let start_i = 0
+	let end_i = 1
+	while (end_i < str.length - 1){
+		//main sliding window loop
+		if (containsOnlyLetters(str.slice(start_i, end_i+1))){
+			end_i++;
+		} else {
+			if (end_i - 1 > start_i || containsOnlyLetters(str.slice(start_i, end_i))){
+				variables.push(str.slice(start_i, end_i).trim())
+			}
+			start_i = end_i;
+			end_i++;
+		}
+	}
+
+	//handle possible variable at the end, possibly because incorrect implementation of sliding window
+	//keeps moving the window start to the end from the last start position
+	//[1+var] => 1+var
+	//1[+var] => +var
+	//1+[var] => var => only letters, add to variables
+	while (start_i < str.length){
+		if (containsOnlyLetters(str.slice(start_i).trim())){
+			variables.push(str.slice(start_i).trim())
+			break;
+		} else {
+			start_i+=1;
+		}
+	}
+	return variables
+}
+
+const replaceVariablesInExp = exp => {
+	let variables = findVariablesInExp(exp);
+	let mod_exp = exp; //Modified expression
+	console.log()
+	console.log(variables)
+	console.log(known_variables)
+	console.log("original exp: " + exp)
+	for (let i = 0; i < variables.length; i++){
+		let variable = variables[i]
+		let loc = mod_exp.indexOf(variable)
+		let value = known_variables[variable]
+		if (value){
+			mod_exp = mod_exp.slice(0, loc) + value + mod_exp.slice(loc + variable.length)
+		}
+		
+	}
+	console.log("modified exp: " + mod_exp)
+	return mod_exp
+}
+
+
+//Creates new entries in known_variables and changes exp only to it's value so that it is displayed as result
+//Example: "radius = 5*2+6" becomes "5*2+6" and known_values["radius"] = evaluate("5*2+6")
+//Note, also applies replaceVariablesInExp 
+const handlePossibleDeclarations = exp => {
+	let loc = exp.indexOf("=")
+	let variable = exp.slice(0, loc).replace(/\s+/g, '')
+	exp = exp.slice(loc+1)
+	exp = replaceVariablesInExp(exp);
+	let result = evaluate(exp)
+	known_variables[variable] = result
+	return exp
+}
 /** @const {string} */
 const currencyUnits = Object.keys(coreConv.currencyUnits).join('|');
 
@@ -93,6 +174,11 @@ const evaluate = exp => {
 };
 
 const main = exp => {
+	if (exp.includes("=")){
+		exp = handlePossibleDeclarations(exp); //Also applies replaceVariablesInExp
+	} else {
+		exp = replaceVariablesInExp(exp);
+	}
 	try {
 		return evaluate(exp)
 			? typeof evaluate(exp) !== 'function' // To filter function printing