- Exceptions to this are B# and E#, which point to the C and F natural keys, respectively; and Bx and Ex, which are the C# and F# keys.
The Purpose of the Double-SharpDouble-accidentals are not seen in any working key signature. In fact, if there were a key signature after C# major (which has the maximum seven sharps), it would contain one F double-sharp (learn more about theoretical key signatures).
In everyday notation, however, double-sharps are necessary in certain scenarios. Suppose you were composing in the key of C# major (which puts a sharp on every note) and wanted to write an A natural in a measure that already contains some A#’s. Instead of alternating between writing A natural and A sharp, you could instead indicate the tone of A natural with a G double-sharp.
The same rules also apply to chords. In an A# major 7th chord – whose notes are A# Cx E# Gx – the tone of A natural is disguised as Gx.
See (♭♭) double-flat.
Memorize the Notes of the Grand Staff
Left Hand Piano Fingering
How to Play Dotted Notes
Piano Chords With Fingering
Chord Types & Their Abbreviations
Easy Bass Piano Chords
Piano Chord Fingering
Diminished Chords & "Dissonance"
Italian Musical Glossary
Beginner Piano Glossary
German Music Terms
Musical Terms A – Z
Piano Terms & Musical Symbols
Reading Musical Rests & Pauses
Music Note Lengths in U.S. & U.K. English
Note Accents & Articulation Marks
Mastering Segno & Coda Repeats