If this is a sample of my spreadsheet, how do I calculate so that the results
will look at both col A and B and sum the total in col C for each variable in
col. A. In other words what is the total amount for A for Jan, Mar...

Col A Col B Col C Col D
a Mar 254 850
a Jan 266 125
c Feb 987 121
c Jan 885 151
a Mar 352 850
b Jan 558 454

Thanks,
Anat