VBA_number the selected code

[amator]

Dear friends,
I've used the attached file method to insert number (in col. A) beside selected code from drop down. I'm in trouble with my file because the records have been extended to more than 50,000 and this make my file heavy so much due to calculating the formula in col. A more than 50,000 times.
would you please tell me, how and which code I can substitute for this formula?

counter.rar


thank you beforehand,

 

[amator]

dear all
would you plz answer my question.I really need it.

thx