I have two colums. One contains Order#, the other the $ amount the of a
discount. If an order has 5items in it, the Order# appear in column A 5 times
with the associated discount for each item. I want to calculate the total
discount by Order#.

Data:

Full Order # Difference

P10890950001 -$5.00
P10962970001 -$13.00
P10948610001 -$25.00
P10948610001 -$15.00
P10731350001 -$10.00
P10731350001 -$4.50
P09494270003 -$20.00
P10878810001 -$12.29
P10866140001 -$39.47
P09604470002 -$22.00
P10895690001 -$6.00
P10895690001 -$6.00