Based on a response to my earlier post, I learned that Excel's autofilter
will only work up to 1000 unique different values max.
I visited MVP Debra D's page http://www.contextures.com/xlautofilter02.html
as was suggested to me, and studied the options given.
I thought the 2nd one which reportedly extracts the first 2 or 3 letters for
use in a "pre-filter", was perhaps closer to providing me with a practical
solution.

However, my situation is a little different i.t.o. data, and I can't quite
figure out how to adapt the given formula viz. =LEFT(C2,2) to suit my
particular dataset.

I have some a column which contains a 7 digit number, with pre-fixed
zero(s). The data is naturally duplicated to roughly 60%, and lies across
some 3630 lines.
In all, I have about 1300 unique number entries, which obviously exceeds the
autofilter capability as was explained.

As I'm a novice at formulas, I would really appreaciate some help with a
suitable formula, that will ultimately consider ALL data down a particular
column in my worksheet, when a user does a "drop down list search".

Kind regards
Maurice