A# 11/A
The A# 11 chord consists of the A# (Perfect unison), D (Major third), F (Perfect fifth), G# (Minor seventh), C (Major ninth) and D# (Perfect eleventh) notes, with A as the bass note.

How to play the A# 11/A chord
- Play A as the lowest bass note in the left hand
- Find A# (Root) on the piano keyboard
- Add D (Major third) — 4 semitones above A#
- Add F (Perfect fifth) — 7 semitones above A#
- Add G# (Minor seventh) — 10 semitones above A#
- Add C (Major ninth) — 14 semitones above A#
- Add D# (Perfect eleventh) — 17 semitones above A#
- Press all 7 notes simultaneously to sound the A# 11/A chord