We love the Nashville Number System! It is a method of transcribing music into numbers based on scale degree. You can read all about the system, but essentially the system allows you to play the same chord chart in any key.
Key of “G”: G Am Bm C D Em F#o
turns into this:
Any key: 1 2m 3m 4 5 6m 7o
The second snippet may look foreign to you, but if you know how to play a major scale, you can write music according to the Nashville system. The 1 represents the first note in the key. Since this song is in the key of “G” the first note is a G – as you can confirm in the first snippet above. The fifth note in the key of “G” is D and the seventh is F#, so the second chord 5/7 represents D/F#.
Not only does the Nashville Number System allow musicians to use the same chart in any key, but it helps cement the relationship chords play to one another as you see the same transitions over and over (ie: 1 4 5 4 or G C D C in “G”).