diff --git a/calculator.html b/calculator.html
new file mode 100644
index 00000000..fc743206
--- /dev/null
+++ b/calculator.html
@@ -0,0 +1,17 @@
+<!DOCTYPE html><html><head>
+<title>Calculator</title><meta charset="utf-8">
+<script type="text/javascript">
+
+function inverse() {
+  var num = document.getElementById("n1");
+  num.value = 1/num.value;
+}
+</script>
+</head>
+<body>
+  Number:
+  <input type="text" id="n1"><p>
+
+  <button onclick="inverse()"> 1/x </button>
+</body>
+</html>
