Display, sort and filter numbers with multiple decimal in excel 2007 -

i'm using excel 2007.

i've list of tasks (200-500) need group in different category/section etc (multiple filters). whole data in excel table can apply excel's build-in table filters display exact data need.

however difficult apply multiple filter display expected data, specially need frequently. make things simple i'm planning number each record like

a.b.c.d.e.f   a, b, c, d, e, f simple numbers. list looks like: 1 1.1 1.2 1.2.1 1.2.1.1 1.2.2 1.3 & on. 

problem is, excel take number single decimal add second decimal, excel treat text, obvious in general behavior.

however, special case, need excel treat both number or text. number preferable want sort them, might difficult text.

to make things little more complex, while filtering in table, require if can add formula filter results 1.* should display numbers starts 1.

is possible excel's default behavior, without vba?

if no, possible vba? if yes, clue appreciated. don't need whole program can write basic vba program, clue how can done?

i sort mine adding helper column adds letter front , sort on that. e.g. 1 becomes f1, 1.1 becomes f1.1 etc. sorted text.

you can use formula ="f" & a1.

my sample:

then data sorted:

and filter: