I run a community center in a developing country where we do low-cost
photocopying.  To help track sales I'm trying to create a sheet that looks
like:
Col A     Col B        Col C      Col D
Date      # copies    price      daily sub-total

Our employee enters the transactions throughout the day.  I want the scheet
to automagically do the daily sub-total, without user intervention.  The
number of transactions varies each day.

I'm looking for a formula for Col D that will check the date of the next row
down.  If it has changed, then run sub-total for the current day's sales.  If
it has not, return a null.  Is that possible?  I've ran a search on "date
subtotal" and looked at all the threads but haven't found my answer.

Thanks for the help!