Калькулятор не нужен...если есть mysql или любой другой sql скиент
с помощью sql-оператора SELECT можно производить вычисления.
Очень удобно кстати:
Server version: 5.1.50-log Gentoo Linux mysql-5.1.50-r1
Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
This software comes with ABSOLUTELY NO WARRANTY. This is free software,
and you are welcome to modify and redistribute it under the GPL v2 license
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql>
mysql> select 2+1
-> ;
+-----+
| 2+1 |
+-----+
| 3 |
+-----+
1 row in set (0.00 sec)
mysql> select sin(2) ;
+-------------------+
| sin(2) |
+-------------------+
| 0.909297426825682 |
+-------------------+
1 row in set (0.02 sec)
mysql> select sin(2)*sin(2)+cos(2)*cos(2);
+-----------------------------+
| sin(2)*sin(2)+cos(2)*cos(2) |
+-----------------------------+
| 1 |
+-----------------------------+
1 row in set (0.01 sec)
mysql>