Major Key Signatures
Flats: The order of flats is B E A D G C F (I memorized this as Bead, Greatest Common Factor). The key is the second flat to the right. For example, four flats is the key of Ab Major.
Sharps: They are in reverse order of flats: F C G D A E B. To find the key, go up a half step from the right-most sharp in the signature. For example, five sharps is the key of B Major (A# is the fifth sharp, and a half step up is B).
Key Signature information from tobyrush.com:
