In key signatures with sharps, the key is determined by the position of the sharps. The last sharp (furthest to the right) indicates the seventh scale degree of the major scale. To find the name of the key, you can go up a half step (one semitone) from the last sharp to find the tonic note of the key.
For example:
- If the key signature has one sharp (F#), the key is G major.
- If there are two sharps (F# and C#), the key is D major.
- With three sharps (F#, C#, and G#), the key is A major.
- Four sharps (F#, C#, G#, D#) indicate E major.
- Five sharps (F#, C#, G#, D#, A#) signify B major.
- Six sharps (F#, C#, G#, D#, A#, E#) mean F# major.
- Seven sharps (F#, C#, G#, D#, A#, E#, B#) correspond to C# major.
To summarize, in key signatures with sharps, the key is determined by the final sharp, which indicates the seventh degree, and the key can be found by going up a half step from that note.