## sum a quantity without listing

I have several order numbers to list, and many have the same part number in
them. User needs a report of the part number, number of occurrences of that
part number, and a total of the quantities for each order that lists the
particular part number. To save space, however, he only wants one instance
of each part number listed. I can't seem to get the total quantity to show
up without actually listing each quantity and doing a sum on the quantity
column. How do I total this column without actually listing it?