Check out auto filter and Grouping in help

"Billsc" wrote:

I need to collapse a series of rows into a single displayed row. I have many
tasks in a single project and want to have only one displayed row per
project but all task numbers in the left column. I can do this by hand but
was looking for a programmtic way to hide a row/column. I wold love to write
formula as
IF A2=A3 then HIDE A*
TIA