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

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