Thank you Arvi. The only time I used ISNA was in a code that was like IF(ISNA(VLOOKUP...) but then it simply became VLOOKUP.
I used the OR to find any number not equal to 1016, 1021 and 1022.
Again, iyaman (this is how we say thank you).

Edit: I added VALUE with the LEFT function to match with the number formatted criteria.
=IF(ISNA(MATCH(VALUE(LEFT($B$4,4)),{1016,1021,1022 },0)),"B","A")