Count different sets of data with multiple variables

I have a spreadsheet with different categories: the first category has options A,B & C and the second category has options 1,2 & 3. What I need excel to do is count the number of items falling under each possible combination of data. I need to know how many times do the combinations A1,A2,A3,B1...etc. appear. The data set I am working with will continue to grow and the number of times each combination appears is important for other calculations in the sheet. Any help would be appreciated!!