A# dim7/A
The A# dim7 chord consists of the A# (Perfect unison), C# (Minor third), E (Diminished fifth) and G (Major sixth) notes, with A as the bass note.

How to play the A# dim7/A chord
- Play A as the lowest bass note in the left hand
- Find A# (Root) on the piano keyboard
- Add C# (Minor third) — 3 semitones above A#
- Add E (Diminished fifth) — 6 semitones above A#
- Add G (Major sixth) — 9 semitones above A#
- Press all 5 notes simultaneously to sound the A# dim7/A chord