In this tutorial, we’ll build a sleek, functional calculator that handles basic arithmetic.Phase 1: The Structure (HTML5)We need a container for our calculator, a display screen, and a grid of buttons. We will use the <input> element for the display and a series of <button> elements for the interface.<!DOCTYPE html><html lang="en"><body> <div class="calculator"> <input type="text" id="display" disabled> <div class="buttons"> <button onclick="clearDisplay()">C</button> <button onclick="appendToDisplay('/')">/</button> <button onclick="appendToDisplay('7')">7</button> <button onclick="appendToDisplay('8')">8</button> <button onclick="appendToDisplay('9')">9</button> <button onclick="appendToDisplay('*')">*</button> <button onclick="appendToDisplay('4')">4</button> <button onclick="appendToDisplay('5')">5</button> <button onclick="appendToDisplay('6')">6</button> <button onclick="appendToDisplay('-')">-</button> <button onclick="appendToDisplay('1')">1</button> <button onclick="appendToDisplay('2')">2</button> <button onclick="appendToDisplay('3')">3</button> <button onclick="appendToDisplay('+')">+</button> <button onclick="appendToDisplay('0')">0</button> <button onclick="calculate()">=</button> </div> </div></body></html>Phase 2: The Look (CSS)A calculator should look like a calculator! We’ll use CSS Grid to organize our buttons neatly into rows and columns..calculator width: 300px; margin: 50px auto; padding: 20px; background: #333; border-radius: 10px;#display width: 100%; height: 40px; margin-bottom: 10px; text-align: right; font-size: 1.5rem;.buttons display: grid; grid-template-columns: repeat(4, 1fr); gap: 10px;button padding: 15px; font-size: 1.2rem; cursor: pointer;Phase 3: The Logic (JavaScript)Now, let’s bring the calculator to life. We need three main functions: one to add numbers to the screen, one to clear the screen, and one to perform the math.const display = document.getElementById("display");function appendToDisplay(input) display.value += input;function clearDisplay() display.value = "";function calculate() try // eval() takes the string and solves the math! display.value = eval(display.value); catch (error) display.value = "Error"; How it works:appendToDisplay: Every time you click a button, its value (number or operator) is appended to the value property of our display input.eval(): This is a built-in JavaScript function that takes a string (like "2 + 2") and evaluates it as code, returning the result (4).try...catch: If a user enters something invalid (like 5++5), the catch block prevents the app from crashing and simply displays "Error" instead.Pro-Tips to Improve Your Project:Add Advanced Math: Incorporate Math.sqrt() or Math.pow() to give your calculator more power.Keyboard Support: Add an event listener to allow users to type numbers using their physical keyboard instead of clicking buttons.Modern Styling: Use CSS variables to create a "Dark Mode" or "Light Mode" toggle.Building this project is a rite of passage for every developer. Once you've got this working, try adding your own unique features! https://calculator.multiplecalculator.com/ !