How do you get 42 keys?
Major Keys: A Major, B Major, C Major, D Major, E Major, F Major, G Major.
Minor Keys: A Minor, B Minor, C Minor, D Minor, E Minor, F Minor, G Minor
Sharp Major Keys: A-Sharp Major, B-Sharp Major, C-Sharp Major, D-Sharp Major, E-Sharp Major, F-Sharp Major, G-Sharp Major
Sharp Minor Keys: A-Sharp Minor, B-Sharp Minor, C-Sharp Minor, D-Sharp Minor, E-Sharp Minor, F-Sharp Minor, G-Sharp Minor
Flat Major Keys: A-Flat Major, B-Flat Major, C-Flat Major, D-Flat Major, E-Flat Major, F-Flat Major, G-Flat Major
Flat Minor Keys: A-Flat Minor, B-Flat Minor, C-Flat Minor, D-Flat Minor, E-Flat Minor, F-Flat Minor, and G-Flat Minor.
Despite enharmonic pairs being a problem here, I still use these when composing. And once, all of them when composing.