Need help, please. I have to compare a large worksheet that has over 50,000 lines and spread into 3 colums. The mission is to search for data in all 3 columns that have the same Op ID, Dept ID and acct No. Once found I need to delete all of the repetitive rows and leave just one row.
The worksheet looks like this:

col A Col B Col C
Op ID dept ID Acct No.
700 350 1125
800 450 1530
900 660 7890
100 770 8760
700 350 1125
700 350 1125
500 450 1125


What I did was filtering the columns and painfully filter all accts that have the same info on Col A and B, then highlighted all the rows that have same info, but the task took forever because the worksheet is so large.

Can anyone help me, please? I am sure there's a better way to accompish this task. I need help from someone who's smarter with me when it comes to Excel. Thanks so much. Chom