G# maj11/C
The G# maj11 chord consists of the G# (Perfect unison), C (Major third), D# (Perfect fifth), G (Major seventh), A# (Major ninth) and C# (Perfect eleventh) notes, with C as the bass note.

How to play the G# maj11/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 G (Major seventh) — 11 semitones above G#
- Add A# (Major ninth) — 14 semitones above G#
- Add C# (Perfect eleventh) — 17 semitones above G#
- Press all 7 notes simultaneously to sound the G# maj11/C chord