Merge branch '加入除法功能'

# Conflicts:
#	index.html

index.html

@@ -12,7 +12,11 @@
   }
 
   function product(a, b) {
-    return a*b;
+    return a * b;
+  }
+
+  function divide(a, b) {
+    return a/b;
   }
 </script>
 </body>