F 3/C
The F 3 chord consists of the F (Perfect unison) and A (Major third) notes, with C as the bass note.

How to play the F 3/C chord
- Play C as the lowest bass note in the left hand
- Find F (Root) on the piano keyboard
- Add A (Major third) — 4 semitones above F
- Press all 3 notes simultaneously to sound the F 3/C chord