Hiding rows based on duplicate numbers in a particular column

Hello all!

I suspect there's an easy way to do this, but I'm tired of trying to figure it out.

I have a sheet of data that's 12 columns by about 900 rows. Column H contains 12 digit numbers, with rows having a duplicate in H grouped together. Is there an easy way to hide all but the first and last instances of each of those groups?

For example, if the row #s (left column below)have the #s in H:
1 401075084894
2 401075084900
3 401075084900
4 401075084900
5 401075084917
6 401075084917
7 401075084917
8 401075084917
9 401075084924
10 401075084931
11 401075084931
12 401075084931
13 401075084931
14 401075084931
15 401075084931
16 401075084931
17 401075084948
18 401075084948
19 401075084948
20 401075084948


I would want to hide rows 3, 6-7, 11-15 and 18-19 so it looks like this:
1 401075084894
2 401075084900
4 401075084900
5 401075084917
8 401075084917
9 401075084924
10 401075084931
16 401075084931
17 401075084948
20 401075084948

I can't use "remove duplicates"; I need to keep all the rows on the sheet. I can't figure out a way to use "Conditional Formatting" to get what I need. Am I missing something obvious?

Thanks

Jenny

Perfect! I knew there had to be something; my brain was too exhausted to see it!

Thank you SO much! I have been wondering about this for a LONNNG time; I just got annoyed enough with it today to actually ask, LOL!

Glad I could help. Sometimes it just takes a fresh pair of eyes

Thanks for the rep point.

Take care.

BSB