I have a worksheet with about 55,000 line items in it regarding sales
history for the past nine months.
* Column A has part numbers. (The same part number can appear multiple
times)
* Column B has the date the order for the part number was received.
* Column C has the date the ordered part number shipped.
* Column D has the number of days elapsed between cols. B and C.

What I would like to do is summarize all this data such that:
* One column lists all the part numbers. (No duplicates!)
* For each part number, I'd like to know how many times the order shipped
within 1-30 days, 31-60 days, 61-90 days, 91-120 days, more than 120 days.

Can anybody help with an Excel formula?

Thanks.
--
Tiziano