A m9
The A m9 chord consists of the A (Perfect unison), C (Minor third), E (Perfect fifth), G (Minor seventh) and B (Major ninth) notes.

How to play the A m9 chord
- Find A (Root) on the piano keyboard
- Add C (Minor third) — 3 semitones above A
- Add E (Perfect fifth) — 7 semitones above A
- Add G (Minor seventh) — 10 semitones above A
- Add B (Major ninth) — 14 semitones above A
- Press all 5 notes simultaneously to sound the A m9 chord