Chord Structure: The Number System

Lesson Goal: To understand the Number System for describing Chord Structure… and to use this system for internalizing commonly-used chord types…

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Prerequisites

Basic music reading skills… the LOVE of music… and the discipline to study and practice.

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Benefits of Learning the Chord Structure Number System

The number system is a commonly-used convention for describing the structure of any kind of chord and enables musicians to talk about chord types and how they are constructed with accuracy, clarity, and ease… as you will discover in the examples below…

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How the Chord Structure Number System Works

The number system for describing chord structure works as follows: Using the major scale as the point of reference, numbers (also called “scale degrees”) are assigned to each note in ascending order…

For example, in the key of C: C=1, D=2, E=3, F=4, G=5, A=6, B=7…

• The number “1” always represents the root of the chord. Always!
• The other numbers correspond to notes in the major scale beginning on the root note.

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Examples of Chord Structures for Commonly Used Chord Types

C Major Triad: Chord Structure = 1-3-5

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C Minor Triad: Chord Structure = 1-b3-5

Yes, you can modify any of the notes using flats…

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C Minor 7th Chord: Chord Structure = 1-b3-5-b7

Yes, you can use any number of notes…

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C Augmented Triad: Chord Structure = 1-3-#5

Yes, you can modify any of the notes using sharps…

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Chord Structures Larger than an Octave

Yes, you can you use notes that go beyond a single octave.

Specifically, chords that include “9ths”, “11ths”, and “13ths” are possible.

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C Major 7, add 9: Chord Structure = 1-3-5-7-9

Yes, any number of notes is possible…

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learn more… Chords & Chord Progressions