G# 9/C#
The G# 9 chord consists of the G# (Perfect unison), C (Major third), D# (Perfect fifth), F# (Minor seventh) and A# (Major ninth) notes, with C# as the bass note.

How to play the G# 9/C# chord
- Play C# as the lowest bass note in the left hand
- Find G# (Root) on the piano keyboard
- Add C (Major third) — 4 semitones above G#
- Add D# (Perfect fifth) — 7 semitones above G#
- Add F# (Minor seventh) — 10 semitones above G#
- Add A# (Major ninth) — 14 semitones above G#
- Press all 6 notes simultaneously to sound the G# 9/C# chord