In key signatures with sharps, the key is determined by looking at the last sharp (the rightmost one). To find the major key, you take the last sharp and go up a half step. The note you reach will indicate the major key. For example:
- If the key signature has one sharp (F♯), it is in the key of G major (the note is G).
- If the key signature has two sharps (F♯ and C♯), it is in the key of D major (the note is D).
- If the key signature has three sharps (F♯, C♯, and G♯), it is in the key of A major (the note is A).
- If the key signature has four sharps (F♯, C♯, G♯, and D♯), it is in the key of E major (the note is E).
- If the key signature has five sharps (F♯, C♯, G♯, D♯, and A♯), it is in the key of B major (the note is B).
- If the key signature has six sharps (F♯, C♯, G♯, D♯, A♯, and E♯), it is in the key of F♯ major (the note is F♯).
- If the key signature has seven sharps (F♯, C♯, G♯, D♯, A♯, E♯, and B♯), it is in the key of C♯ major (the note is C♯).
For minor keys, you can find the relative minor by going down a minor third (or three half steps) from the major key.