Trouble with replacing action

Hello all. I just can't seem to get this right, and wondered if someone could help;

I am trying to get unwanted characters off the end of the TRACK field.

Sometimes the track field has album tracks as 01/14, 02/13, 04/14 etc. (eg. for a 14 track album)
I want to change these to 1,2,3,4, etc,
I can do the bit to get rid of the leading 0, but I just can't seem to get rid of the /?? bit (if it exists).
TIA :unsure:

Action type: Format value
Field: TRACK
Formatstring: [$num(%track%,1)]

Thanks