diff --git a/jsq.html b/jsq.html
index 78e7422..8b8ecf5 100644
--- a/jsq.html
+++ b/jsq.html
@@ -82,6 +82,7 @@
         <button onclick="compute()">=</button>
         <button onclick="chooseOperation('+')">+</button>
         <button onclick="chooseOperation('%')">%</button>
+        <button onclick="appendNumber('-')">±</button>
     </div>
 </div>
 
@@ -94,6 +95,7 @@
 
     function appendNumber(number) {
         if (number === '.' && currentOperand.includes('.')) return;
+        if (number === '-' && currentOperand.length > 0) return; // 防止在数字中间添加负号
         currentOperand += number;
         updateDisplay();
     }
@@ -150,4 +152,4 @@
     }
 </script>
 </body>
-</html>
\ No newline at end of file
+</html>