Start learning how to play the piano today with flowkey:. 2 5 ones, frequently jotted down with roman characters (ii V I) are possibly the most effective chord progression for rapidly and efficiently modulating to and from any key. On top of that, they just sound so rewarding and jazzy. From Coltrane to The Beatles to Maroon 5 you can find 2 5 ones in every corner of popular music! And, an extra special…