Numbers – scales and chords

A lot of musician refer to notes and chords by their ‘number’ refering to their position in the scale.

R, 2, 3, 4, 5, 6, 7

In C that would be

C = 1
D = 2
E = 3
F = 4
G = 5
A = 6
B = 7

So when someone refers to the “6th” that’s the A when in C Major.

Other scales work the same way, just start on a different note, ie. the scale G

G = 1
A = 2
B = 3
C = 4
D = 5
E = 6
F# = 7

The Nashville Numbering System uses numbers as above to denote chords – 1, 4, 5 in the key of G would have chords G Major, C Major and D Major

Some people use Roman Numerals for chords:

ie. In the scale of C Major

I = C Major
ii = D Minor
iii = E Minor
IV = F Major
V = G Major
vi = A Minor
vii° = B diminished

Note the use of capitals to denote major chords and lowercase to denote minor chords.

A note about the blues (and some rock and some country) – the Major chords (I, IV and V) are played as Dominant 7ths (flat 7ths) rather than Major 7ths – which gives that bluesy feel to the progression. According to theory that is playing the ‘wrong’ chords – but theory is just a starting point, and if a chord progression sounds good; play it.

So when someone calls out “I, IV, V” (actually they say “one, four, five in the key of X”  – X being whatever key they want to play in. They may also say “Blues in the key of X” which means the same thing.)

The chord structure will be 12 bars - one chord per bar:
 I,  I,  I, I
 VI, VI, I, I
 V,  IV, I, V
In the key of G the chords would be - one chord per par:
 G7, G7, G7, G7
 C7, C7, G7, G7
 D7, C7, G7, D7

In some songs, the last chord is the I instead of the V. Also, the second bar may go to the IV chord.

And of course there are other variations – but that structure will cover you for a lot of blues, rock and country.

You may see a chart where the “I” may be an “i” – which means you’re in a minor scale and the ‘root’ is a minor chord.


–> So let’s now explore the CAGED system

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