23/05/2025
Do you know Number System?
The number system is a way to represent chords using numbers instead of chord names. Each number corresponds to a scale degree in a key. So instead of saying "C major, F major, G major," you'd say "1, 4, 5" β because those chords are built on the 1st, 4th, and 5th notes of the C major scale.
This system is relative, meaning it works in any key. You just need to know the scale you're in.
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π‘ How It Works
Letβs say youβre in the key of C major. The C major scale is:
C, D, E, F, G, A, B
Each of these notes is given a number from 1 to 7:
C is 1
D is 2
E is 3
F is 4
G is 5
A is 6
B is 7
Now, when we build chords on each of those notes using the notes from the scale, we get:
1 becomes C major
2 becomes D minor
3 becomes E minor
4 becomes F major
5 becomes G major
6 becomes A minor
7 becomes B diminished
So a chord progression like C β G β Am β F would be written in numbers as 1 β 5 β 6m β 4
The βmβ after the 6 just means itβs a minor chord.
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π΅ Why Use Numbers?
Because this system is key-independent. If you want to play the same progression in G major, you donβt need to re-figure it out. You just apply the same numbers to the G major scale:
G is 1
D is 5
E minor is 6m
C is 4
So that same progression becomes G β D β Em β C
Still 1 β 5 β 6m β 4, just in a different key.
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βοΈ Notation Tips
Minor chords: write βmβ after the number (e.g., 6m)
Dominant 7 chords: write β7β (e.g., 5β·)
Suspended chords: add βsusβ (e.g., 4sus)
Inversions: use slash notation (e.g., 5/7 means the 5 chord with the 7th note of the scale in the bass)
Augmented or diminished chords: might be marked as β+β or βΒ°β (though less common in basic pop/rock)
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π€ Common Progressions in Numbers
1 β 4 β 5 (basic rock/blues)
1 β 5 β 6m β 4 (used in countless pop songs)
6m β 4 β 1 β 5 (the "sensitive