I have a spreadsheet with 38000 rows of data. The data comes in with date
(01/01/01) in column A and time (12:00:00) in Column B. The data is recorded
every 5 secs.

I would only want to keep data every 5 mins and delete the rest. I gather
this can be done in two ways:

1) by deleting 'x' number of rows below the first data and repeat the process.

2) by matching values **:00:00, **:05:00, **:10:00 and such in Column B and
deleting the rest of the columns.

Can anyone help me with a macro to do this?

Many thanks.