What Numbers Mean in a Chord Progression In a chord progression, numbers represent the scale degrees of a key. Instead of calling chords by their letter names (like C, F, G), we use numbers (like 1, 4, 5) to show their position in the major scale. For example, in the key of C major: 1 = C major 2 = D minor 3 = E minor 4 = F major 5 = G major 6 = A minor 7 = B diminished Using numbers makes it easy to play the same progression in any key. So if someone says 1–5–6–4, you can play it in C, G, F, or