thinkswell · AdyaTech · Dec 24, 2025
diff --git a/Calculator/AdyaTech/README.md b/Calculator/AdyaTech/README.md
@@ -0,0 +1,45 @@
+# Calculator App 
+
+A simple interactive **Calculator App** built using **HTML, CSS and JavaScript**. 
+
+---
+
+### ✅ Input Validation & Error Handling Improvements
+
+### 1. Division by Zero Handling
+- Added explicit checks to prevent division by zero.
+- When a division by zero is detected, the calculator displays **"Error"** instead of returning `Infinity`.
+- The calculator safely stops further calculation until cleared.
+
+---
+
+### 2. Prevention of Consecutive Operators
+- Restricted users from entering multiple operators consecutively (e.g. `5 ++ 3`).
+- If an operator is entered after another operator, the previous operator is automatically replaced.
+- Ensures valid mathematical expressions at all times.
+
+---
+
+### 3. Decimal Point Validation
+- Prevented multiple decimal points within a single number (e.g. `3.1.4`).
+- The calculator now checks the current number segment before allowing a decimal.
+- Eliminates parsing and calculation errors.
+
+---
+
+### ⌨️ Keyboard Support Added
+
+The calculator now supports full keyboard input:
+
+- **Numbers:** `0–9`
+- **Operators:** `+  -  *  /`
+- **Decimal:** `.`
+- **Enter / =** → Calculate result
+- **Backspace** → Delete last character
+- **Escape (Esc)** → Clear input
+
+Keyboard operators `*` and `/` are internally mapped to `×` and `÷`.
+
+---
+
+
diff --git a/Calculator/AdyaTech/index.html b/Calculator/AdyaTech/index.html
@@ -0,0 +1,46 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <link rel="stylesheet" href="style.css">
+    <title>Calculator</title>
+</head>
+<body>
+    <div class="calculator">
+  <div class="input" id="input"></div>
+  <div class="buttons">
+    <div class="operators">
+      <div>+</div>
+      <div>-</div>
+      <div>&times;</div>
+      <div>&divide;</div>
+    </div>
+    <div class="leftPanel">
+      <div class="numbers">
+        <div>7</div>
+        <div>8</div>
+        <div>9</div>
+      </div>
+      <div class="numbers">
+        <div>4</div>
+        <div>5</div>
+        <div>6</div>
+      </div>
+      <div class="numbers">
+        <div>1</div>
+        <div>2</div>
+        <div>3</div>
+      </div>
+      <div class="numbers">
+        <div>0</div>
+        <div>.</div>
+        <div id="clear">C</div>
+      </div>
+    </div>
+    <div class="equal" id="result">=</div>
+  </div>
+</div>
+<script src="script.js"></script>
+</body>
+</html>
diff --git a/Calculator/AdyaTech/script.js b/Calculator/AdyaTech/script.js
@@ -0,0 +1,178 @@
+"use strict";
+
+var input = document.getElementById("input"),
+  number = document.querySelectorAll(".numbers div"),
+  operator = document.querySelectorAll(".operators div"),
+  result = document.getElementById("result"),
+  clear = document.getElementById("clear"),
+  resultDisplayed = false;
+
+// =====================
+// Helper Functions
+// =====================
+function isOperator(char) {
+  return char === "+" || char === "-" || char === "×" || char === "÷";
+}
+
+function backspace() {
+  if (resultDisplayed) {
+    input.innerHTML = "";
+    resultDisplayed = false;
+  } else {
+    input.innerHTML = input.innerHTML.slice(0, -1);
+  }
+}
+
+function addValue(value) {
+  var currentString = input.innerHTML;
+  var lastChar = currentString[currentString.length - 1];
+
+  // Prevent multiple decimals in one number
+  if (value === ".") {
+    var parts = currentString.split(/\+|\-|\×|\÷/);
+    if (parts[parts.length - 1].includes(".")) return;
+  }
+
+  if (!resultDisplayed) {
+    input.innerHTML += value;
+  } else if (resultDisplayed && isOperator(lastChar)) {
+    resultDisplayed = false;
+    input.innerHTML += value;
+  } else {
+    resultDisplayed = false;
+    input.innerHTML = value;
+  }
+}
+
+// =====================
+// Number Buttons
+// =====================
+for (var i = 0; i < number.length; i++) {
+  number[i].addEventListener("click", function (e) {
+    addValue(e.target.innerHTML);
+  });
+}
+
+// =====================
+// Operator Buttons
+// =====================
+for (var i = 0; i < operator.length; i++) {
+  operator[i].addEventListener("click", function (e) {
+    var currentString = input.innerHTML;
+    var lastChar = currentString[currentString.length - 1];
+
+    if (currentString.length === 0) return;
+
+    if (isOperator(lastChar)) {
+      input.innerHTML =
+        currentString.substring(0, currentString.length - 1) +
+        e.target.innerHTML;
+    } else {
+      input.innerHTML += e.target.innerHTML;
+    }
+  });
+}
+
+// =====================
+// Equal Button
+// =====================
+result.addEventListener("click", calculate);
+
+function calculate() {
+  var inputString = input.innerHTML;
+  if (inputString.length === 0) return;
+
+  var numbers = inputString.split(/\+|\-|\×|\÷/g);
+  var operators = inputString.replace(/[0-9]|\./g, "").split("");
+
+  // Division
+  var divide = operators.indexOf("÷");
+  while (divide !== -1) {
+    if (numbers[divide + 1] == 0) {
+      input.innerHTML = "Error";
+      resultDisplayed = true;
+      return;
+    }
+    numbers.splice(divide, 2, numbers[divide] / numbers[divide + 1]);
+    operators.splice(divide, 1);
+    divide = operators.indexOf("÷");
+  }
+
+  // Multiplication
+  var multiply = operators.indexOf("×");
+  while (multiply !== -1) {
+    numbers.splice(multiply, 2, numbers[multiply] * numbers[multiply + 1]);
+    operators.splice(multiply, 1);
+    multiply = operators.indexOf("×");
+  }
+
+  // Subtraction
+  var subtract = operators.indexOf("-");
+  while (subtract !== -1) {
+    numbers.splice(subtract, 2, numbers[subtract] - numbers[subtract + 1]);
+    operators.splice(subtract, 1);
+    subtract = operators.indexOf("-");
+  }
+
+  // Addition
+  var add = operators.indexOf("+");
+  while (add !== -1) {
+    numbers.splice(
+      add,
+      2,
+      parseFloat(numbers[add]) + parseFloat(numbers[add + 1])
+    );
+    operators.splice(add, 1);
+    add = operators.indexOf("+");
+  }
+
+  input.innerHTML = numbers[0];
+  resultDisplayed = true;
+}
+
+// =====================
+// Clear Button
+// =====================
+clear.addEventListener("click", function () {
+  input.innerHTML = "";
+  resultDisplayed = false;
+});
+
+// =====================
+// Keyboard Support
+// =====================
+document.addEventListener("keydown", function (e) {
+  if (e.key >= "0" && e.key <= "9") {
+    addValue(e.key);
+  }
+
+  if (e.key === ".") {
+    addValue(".");
+  }
+
+  if (e.key === "+" || e.key === "-") {
+    addValue(e.key);
+  }
+
+  if (e.key === "*") {
+    addValue("×");
+  }
+
+  if (e.key === "/") {
+    addValue("÷");
+  }
+
+  if (e.key === "Enter" || e.key === "=") {
+    e.preventDefault();
+    calculate();
+  }
+
+  if (e.key === "Backspace") {
+    backspace();
+  }
+
+  if (e.key === "Escape") {
+    input.innerHTML = "";
+    resultDisplayed = false;
+  }
+});
diff --git a/Calculator/AdyaTech/style.css b/Calculator/AdyaTech/style.css
@@ -0,0 +1,123 @@
+body {
+  width: 500px;
+  margin: 4% auto;
+  font-family: 'Source Sans Pro', sans-serif;
+  letter-spacing: 5px;
+  font-size: 1.8rem;
+  -moz-user-select: none;
+  -webkit-user-select: none;
+  -ms-user-select: none;
+}
+
+.calculator {
+    height: 500px;
+  padding: 20px;
+  -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  border-radius: 1px;
+}
+
+.input {
+  border: 1px solid #ddd;
+  border-radius: 1px;
+  height: 60px;
+  padding-right: 15px;
+  padding-top: 10px;
+  text-align: right;
+  margin-right: 6px;
+  font-size: 2.5rem;
+  overflow-x: auto;
+  transition: all .2s ease-in-out;
+}
+
+.input:hover {
+  border: 1px solid #bbb;
+  -webkit-box-shadow: inset 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  box-shadow: inset 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+}
+
+.buttons {}
+
+.operators {}
+
+.operators div {
+  display: inline-block;
+  border: 1px solid #bbb;
+  border-radius: 1px;
+  width: 80px;
+  text-align: center;
+  padding: 10px;
+  margin: 20px 4px 10px 0;
+  cursor: pointer;
+  background-color: #ddd;
+  transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
+}
+
+.operators div:hover {
+  background-color: #ddd;
+  -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  border-color: #aaa;
+}
+
+.operators div:active {
+  font-weight: bold;
+}
+
+.leftPanel {
+  display: inline-block;
+}
+
+.numbers div {
+  display: inline-block;
+  border: 1px solid #ddd;
+  border-radius: 1px;
+  width: 80px;
+  text-align: center;
+  padding: 10px;
+  margin: 10px 4px 10px 0;
+  cursor: pointer;
+  background-color: #f9f9f9;
+  transition: border-color .2s ease-in-out, background-color .2s, box-shadow .2s;
+}
+
+.numbers div:hover {
+  background-color: #f1f1f1;
+  -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  border-color: #bbb;
+}
+
+.numbers div:active {
+  font-weight: bold;
+}
+
+div.equal {
+  display: inline-block;
+  border: 1px solid #3079ED;
+  border-radius: 1px;
+  width: 17%;
+  text-align: center;
+  padding: 127px 10px;
+  margin: 10px 6px 10px 0;
+  vertical-align: top;
+  cursor: pointer;
+  color: #FFF;
+  background-color: #4d90fe;
+  transition: all .2s ease-in-out;
+  position: relative;
+  left: 358px;
+  bottom: 300px;
+}
+
+div.equal:hover {
+  background-color: #307CF9;
+  -webkit-box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  box-shadow: 0px 1px 4px 0px rgba(0, 0, 0, 0.2);
+  border-color: #1857BB;
+}
+
+div.equal:active {
+  font-weight: bold;
+}
+