1.11Why numbers matter for playing by ear

Imagine you hear a melody:

до – до – соль – соль – ля – ля – соль

You may recognize it as:

C C G G A A G

But functionally, in C:

1 1 5 5 6 6 5

Now suppose somebody says:

“Play it in G.”

You don't need to calculate each note independently.

G major:

G A B C D E F♯

So:

1 1 5 5 6 6 5

becomes:

G G D D E E D

That is the power of scale-degree thinking.

It turns transposition from memorization into mapping.