A query about conditional formatting using excel.

I am a music teacher. I use excel to document pupil's achievement. A cell
for each pupil in the register is included to identify who has instrumental
knowledge and grades.

I record, in code, the instruments and levels gained of my musicians in
school.

This code goes as follows;

Piano grade 3 = P3, Trumpet grade 5 = T5, Trombone grade 6 = Tr6, Tuba grade
2 = Tu2 etc.

Can I "conditionally" route out the numerical part of the code, in a
wildcard fashion, to then highlight and identify "greater than or equal to"
various instrumental grades of 3 and higher for my gifted and talented
musicians?

Version: Microsoft Excel 2002 (10.6829.6830) SP3

Many Thanks,