These chords are usually written in Roman numerals, and if the chord is minor it's usually written IIm, VIm and so on. This progression is the classic I-IV-V chord run at the heart of countless ro ...

Chords are numbered in Roman numerals. For example, in the scale of C major, the chords are numbered like this: An added 6th is a major triad with the addition of a 6th note above the root.