There are User Defined Functions that can be called within a cell much like =left(A1,2) etc.
To access the UDFs, press the function button as shown below and select 'Essential Excel Add-In' from the list of categories. The list of available UDFs is shown. Click on a UDF to bring up the function popup.
Created with the Personal Edition of HelpNDoc: Single source CHM, PDF, DOC and HTML Help creation