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

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