The key field, is in the Adjustments menu which can be in-mode and faded out mode will change depending on the selected computer mode. 

Delete input field and/or last value (on keyboard [DEL])

Delete current calculation (on keyboard [ESC])

Change computer mode (on keyboard [<])

In the Windows Pocket PC mode and in the commercial desktop Calculator mode

VAT or [ F4 ]

Subtotal

Percent calculation (on keyboard [F3] or [P])

Reciprocal

Root calculation

In the formula computer mode

Open bracket calculation

Close bracket calculation

Copyright 2001-2005