Why the Number System is So Powerful in Music

If there's one aspect of piano playing I wished my traditional piano lessons would have included, it would be the number system for piano. But that wasn't in the criteria.

The number system is so powerful in music because it is a structural representation of keys of music, chords and chord progressions.  It ultimately makes it easier to understand these elements of music.

Traditional piano lessons are about notes not numbers. Don't get me wrong. One needs to know the notes of any given key of music, chord, progression, scale, etc. But knowing the number system for piano takes an aspiring piano player to a higher level.

Why numbers are better than notes.

Every key of music has a different sequence of notes entirely. For example, the key of F Major is its own unique key.

The notes being F G A Bb C D E make it the only key of music with those specific notes in that specific order.

The key of B flat Major is uniquely different.The notes being Bb C D Eb F G A make it the only Major key with those specific notes. And even though F Major and B flat Major are separated by only one note (Eb), they're not the same key.

What makes them different? One word can answer this question. Structure.

Every note (or tone) has a function within the Major key. In fact, the best way to understand these functions is to take a quick look at the technical names of these notes. But I'll take it a step further and explain the meaning of each one.

As you've seen there are 7 different notes (or tones) in a Major key of Music. Let's look at each tone and its corresponding technical name in the key of C Major.

The first note in the key is called the tonic. This is actually the note the key is named after. It's this note that the tonic triad (3 note chord) is built upon. In this case it is C Major.The second note in the key is called the supertonic. The name doesn't imply that it's superior to the tonic. It's just based on a Latin word that means above or after. One way to remember this tone, is that it supersedes or comes after the tonic.The third note in the key is called the mediant. It's based on a Latin word that means middle. It's not in the middle of the key but instead is in the middle of the tonic and the dominant (which we haven't covered yet).

The fourth note in the key is called the subdominant. It's positioned a 5th (interval) below the tonic in contrast the the dominant which is a 5th above it. That's how it gets it's name. The fifth note in the key is called the dominant because it has a very strong relationship with the tonic. So much so, that it's "dominant" among any other note within the key. For example, the 5th has a very strong pull to the tonic, especially when a chord is built upon this note.

The sixth note in the key is called the submediant. It's a 3rd interval below the tonic as the mediant which is a 3rd above it. That's how it gets it's name.The seventh note in the key is called the leading tone. This is easy to remember because when the 7th note is a melody note, it very often will lead into the tonic. Why? Because they're a half step apart and this has a very strong aural pull to the tonic.

You can see from these technical note names that each tone has a structural function in the key. What could make understanding music easier? The number system of course!

When you know the number sequence of any key of music, it becomes very easy to navigate because you know the structure of the tones.

For example, if you have a song that calls for playing the 2-5-1 chord progression and you're in the key of C Major, you know that it's going to be a D chord to a G chord to a C chord.

But if you have the same 2-5-1 chord progression but in the key of D Major, I automatically know that it's not going to be those tones. Instead it would be an E chord to an A chord to a D chord

When you realize that there are 10 other Major keys that you can instantly determine the chords in, you can see how powerful it is to know the number system for piano.

And what about chords themselves? Knowing the number system for piano takes away the confusion for creating chords and voicings.

For example, at the most basic level, you know that a Major triad consist of the 1st, 3rd and 5th tones of any key. Of course they're easily recognizable when they're in root position.

But what about when you have an open voicing? The good news is that the structure is easily recognizable because no matter how open the voicing may be, it's easily recognizable and that takes the confusion and frustration out of music.

When chords become more complex with advanced voicings and tones, the number system for piano allows you to easily understand and play those chords even across several keys of music.