Didn't you love doing those color-by-number things when you were a kid? I did. I wasn't terribly creative growing up, and I was very happy to let someone else take the responsibility for figuring out what color to put where. Under this arrangement, I didn't have to waste time agonizing over endless shades and hues, and I could concentrate fully on what I really wanted to do: coloring.
Breaking music down into numbers provides the same type of freedom. You don't have to concentrate as much on the mechanics, which means you can focus on actually making music.
The advantage of using numbers over letters is that it allows you to think independently of keys. (We already saw that songs retain the same sound and structure regardless of what key they are played in.) Although it is a bit more work up front, learning the number method really pays off in increased flexibility and confidence later on.
My first instrument was not the piano, it was the harmonica. (You could justifiably say I entered the world of music theory through the back door.) The harmonica player has an almost unfair advantage in understanding the number method. When a harmonica player wants to switch keys, he simply picks up a different harmonica and plays the same pattern of notes. What the number method does is take this principle and make it practicable on any instrument.
There is nothing original about the number method - it is the same idea behind singing Do-Re-Mi-Fa-So-La-Ti-Do to teach the relationships within the major scale. When using the number method, Do, the tonic or "root", is always 1, and the numbers count up the major scale from there. This is not Sudoku.
This simple chart is the foundation of the whole method. Using this chart, you can quickly locate the numeric equivalent for any note in any key, and the letter equivalent for any number in any key, until you have a firm enough grasp on the system to figure it out in your head. In time, this will become automatic.
If all this business about numbers still doesn't make sense to you, don't worry. It will soon. For now, work through the exercises below and feel free to ask for clarification on any point in the comments.
Putting it into Practice
- What is #5 in the key of D? #7 in the key of E? #2 in the key of Ab?
- What number describes F in the key of C? E in the key of G? F in the key of Db?
- Play a song you know well, but instead of singing the words to the melody, sing the numbers to the melody. (If you hate math and find it awkward to sing numbers, use the Do-Re-Mi scale.) Repeat with other songs. The goal is to understand the independence of melodic structures from their particular given key.
- When you're listening to songs you have not seen the music for, try and decipher what the melody is doing in terms of numbers. (You don't need to bother about what key the song is in.) This is often surprisingly easy, especially with simpler songs. When you're playing worship, you will need to know exactly where the melody is at all times, so you can insert the appropriate transitions, harmonies, and improvisational embellishments.