Index + Match/Multi-Vlookup for Items with shared names

Hi all, I'm having a problem that is giving me a major headache, hoping someone here can help me out.

Sample.xlsx

In the attached excel file, I'm trying to do a lookup based on two criteria - the class and the number. I used an index/match combo that I think should work, but it didn't register correctly. I keep on getting an error.

I believe this may be due to the fact that there are shared values - some numbers are shared across multiple classes. If that's the case, is there a workaround so that I can properly lookup the item? If not with the index/match, with any other function? (I've tried a vlookup in this case but no luck either)

Thanks!

Fascinating, I never knew that arrays had to be inputed differently. You learn something every day - thank you Tony Valko, I appreciate your expertise and assistance!