Hi - does anyone have any experience with using Excel to count letters in excel?

Eg I have an excel file with many grades in it, the grades are letters rather than numbers, so A, B, C, etc.

We are looking for a way to count the number of A's, B's, C's etc across the whole spreadheet.

I am weak at excel and can do basic number forumas but am stumbed by counting Text.

Cheers

Butuz