One might first think the Windows 7 calculator looks a lot like previous incarnations of the classic Windows calculator. However, in Windows 7, Microsoft added a myriad of new calculating features. You can switch to Scientific mode, Programmer mode or Statistics mode. You can also perform conversions and calculate time between dates. In addition to that, you can calculate fuel economy, vehicle lease payments and even your mortgage! The new Windows 7 calculator also includes a Calculation History area, so you can review your past calculations. Below is a link from Microsoft that explores all of the seemingly hidden options and explains their operation.

windows.microsoft.com