Question: how many combinations on a guitar?
Answer: 1 string, 6c1 = 6 combinations (i.e. String 1, 2, 3, 4, 5 or 6) 2 string chords, 6c2 = 15 combinations (i.e. strings 1, 2 or say 2, 3 or 1, 3 etc) 3 string chords, 6c3 = 20 combinations. 4 string chords, 6c4 = 15 combinations.