diff --git a/Projects/1-Beginner/Calculator.html b/Projects/1-Beginner/Calculator.html
index ec6e0397..215091fe 100644
--- a/Projects/1-Beginner/Calculator.html
+++ b/Projects/1-Beginner/Calculator.html
@@ -82,11 +82,11 @@
             <button class="clear" onclick="clearAll()">AC</button>
             <button class="clear" onclick="clearEntry()">C</button>
             <button class="operator" onclick="appendOperator('%')">%</button>
-            <button class="toggle-sign" onclick="toggleSign()">+/-</button>
+            <button class="operator" onclick="appendOperator('÷')">÷</button>
             <button onclick="appendDigit('7')">7</button>
             <button onclick="appendDigit('8')">8</button>
             <button onclick="appendDigit('9')">9</button>
-            <button class="operator" onclick="appendOperator('÷')">÷</button>
+            <button class="operator" onclick="appendOperator('×')">×</button>
             <button onclick="appendDigit('4')">4</button>
             <button onclick="appendDigit('5')">5</button>
             <button onclick="appendDigit('6')">6</button>
@@ -95,8 +95,9 @@
             <button onclick="appendDigit('2')">2</button>
             <button onclick="appendDigit('3')">3</button>
             <button class="operator" onclick="appendOperator('+')">+</button>
-            <button onclick="appendDigit('0')" style="grid-column: span 2;">0</button>
+            <button onclick="appendDigit('0')">0</button>
             <button onclick="appendDigit('.')">.</button>
+            <button class="toggle-sign" onclick="toggleSign()">+/-</button>
             <button class="equals" onclick="calculate()">=</button>
         </div>
     </div>
@@ -190,18 +191,24 @@
                     clearAll();
                     return;
                 }
+                operator = '';
+                previousInput = '';
                 currentInput = '';
-                let lastValidInput = '';
+                let buffer = '';
                 for (let item of history) {
-                    if (/[0-9.]/.test(item)) {
-                        currentInput += item;
-                        lastValidInput = currentInput;
-                    } else if (item !== '+/-') {
+                    if (item === '+/-') {
+                        buffer = buffer
+                            ? (buffer.startsWith('-') ? buffer.slice(1) : '-' + buffer)
+                            : '-';
+                    } else if (/[0-9.]/.test(item)) {
+                        buffer += item;
+                    } else {
+                        previousInput = buffer;
                         operator = item;
-                        previousInput = lastValidInput;
-                        currentInput = '';
+                        buffer = '';
                     }
                 }
+                currentInput = buffer;
                 expression = operator ? `${previousInput}${operator}${currentInput}` : currentInput || '0';
             } else {
                 clearAll();