A 7
The A 7 chord consists of the A (Perfect unison), C# (Major third), E (Perfect fifth) and G (Minor seventh) notes.

How to play the A 7 chord
- Find A (Root) on the piano keyboard
- Add C# (Major third) — 4 semitones above A
- Add E (Perfect fifth) — 7 semitones above A
- Add G (Minor seventh) — 10 semitones above A
- Press all 4 notes simultaneously to sound the A 7 chord