I used $num(%_counter%,2) %title%
this worked very well.
my next question is there a way of avoiding selecting each album. i.e select all folders and apply the conversion once?
Gary
%_counter% works on all selected files and is not reset to 1. So if you have selected, say, 500 files, %_counter% will count from 1 to 500.
If you want to get a reset for each folder, you would have to use the track numbering wizard.