"Harlan Grove" wrote
=RIGHT(LEFT(A1,FIND(".xls]",A1)-1),6+ISNUMBER(-MID(A1,FIND(".xls]",A1)-7,1)))

May be [building on your idea] even like this:

=LOOKUP(1E+307,--RIGHT(LEFT(A1,FIND(".xls]",A1)-1),{6,7}))

Regards,
KL