A counting problem

[Don Rountree]

I have a list of customers for my sales reps. Column A
contains the sales rep's number. Column B contains the
customer number. Column C contains the sales for the
customer for the current month. I would like to write a
formula that will count the customers that have purchased
by sales rep. I would appreciate any help given.
Thanks...

Don Rountree

 

[Don Guillett]

try
=sumproduct((rngA=123)*(rngB))
to count the number of customers for salesman 123
=sumproduct((rngA=123)*(rngB=456)*rngC)
to sum the sales for salesman 123 and customer 456