diff --git b/calculadora.html a/calculadora.html
new file mode 100644
index 0000000..6f7aa53
--- /dev/null
+++ a/calculadora.html
@@ -0,0 +1,42 @@
+<!DOCTYPE html>
+<html>
+<head>
+	<title>calculadora</title>
+</head>
+<body>
+	<form>
+		<table border="2px" width="200" align="center">
+			<tr>
+			<td colspan="4" style="height: 20px"><input type="text" name="mostrar"></td>
+			</tr>
+			<tr>
+			<td><input type="button" value="7" name="7" onclick="mostrar.value+='7'"></td>
+			<td><input type="button" value="8" name="8" onclick="mostrar.value+='8'"></td>
+			<td><input type="button" value="9" name="9" onclick="mostrar.value+='9'"></td>
+			<td><input type="button" value="-" name="-" onclick="mostrar.value+='-'"></td>
+			</tr>
+			<tr>
+			<td><input type="button" value="4" name="4" onclick="mostrar.value+='4'"></td>
+			<td><input type="button" value="5" name="5" onclick="mostrar.value+='5'"></td>
+			<td><input type="button" value="6" name="6" onclick="mostrar.value+='6'"></td>
+			<td><input type="button" value="+" name="+" onclick="mostrar.value+='+'"></td>
+			</tr>
+			<tr>
+			<td><input type="button" value="1" name="1" onclick="mostrar.value+='1'"></td>
+			<td><input type="button" value="2" name="2" onclick="mostrar.value+='2'"></td>
+			<td><input type="button" value="3" name="3" onclick="mostrar.value+='3'"></td>
+			<td><input type="button" value="*" name="*" onclick="mostrar.value+='*'"></td>
+			</tr>
+			<tr>
+			<td><input type="button" value="C" name="C" onclick="mostrar.value=' '"></td>
+			<td><input type="button" value="0" name="0" onclick="mostrar.value+='0'"></td>
+			<td><input type="button" value="=" name="=" onclick="mostrar.value=eval(mostrar.value)"></td>
+			<td><input type="button" value="/" name="/" onclick="mostrar.value+='/'"></td>
+			</tr>
+	</table>
+		
+	</form>
+	
+
+</body>
+</html>
\ No newline at end of file
