Number TAB uses numbers to represent fingerings for the Native American style flute. Here are the fingerings for the pentatonic minor scale and the numbers assigned to each one:

With Number TAB you can write down your ideas quickly by using just one number per note, rather than using six finger hole symbols. A single number is much easier to read, and faster to write than six finger holes. For example, the scale shown above can be written simply as:

This will work for any musical idea, in any key. Here are some examples:

Since Number TAB is only a shortcut for fingerings it works on any standard NAF, in any key.

So where do the numbers come from?
The numbers used in Number TAB are derived from a practice of numbering (and naming) the notes of a scale. These are referred to as Scale Degrees. Scale degrees describe a note's position and function in the scale. This practice started with seven note scales which are the most common type of scale in Western music. The best known seven note scale is the major scale. You might know it as the Do-Re-Mi scale:

Scale degrees assign a number to each note, starting with the lowest note, Do, as note 1.

We can now easily see that there are seven notes in this scale and that Do is repeated (twice as high in pitch) as the number 8. Another name for this note is Octave (Latin for eight.)

If we remove the Do-Re-Mi syllables we now see the notes of the scale as numbers.

A minor scale also has seven notes, therefore the same scale degrees shown above can be used to describe a minor scale.

Scale Degree Numbers and Pentatonic Scales
The Native American style flute plays a pentatonic, (5 note), minor scale. Pent (πέντε) is ancient Greek for five, and can be found in words like "pentagon".

You can think of a pentatonic scale as a seven note scale with two notes removed.

To create the pentatonic scale called a pentatonic minor we start with a full (seven note) minor scale and remove two of its scale degrees. Specifically scale degrees 2, and 6.

However, even though scale degrees 2 and 6 are not part of a pentatonic minor scale they have not disappeared. You can still play 2 if you half-hole the bottom hole, and 6 by uncovering the four bottom holes.

Since notes 2 and 6 are still there, the scales degrees that make up the pentatonic minor scale retain their position from the original seven note scale. This is why Number TAB displays the pentatonic minor scale without the 2 or 6:

Number TAB and other TAB systems
In addition to being a quicker way to write or read music for the NAF, Number TAB also bridges the gap between finger charts and tablature systems for the NAF that use music notation.

As illustrated in the diagram below, the Number TAB numbers (located at the bottom) directly correspond to the interval names, fingerings and "notes" directly above them. The music notation system shown is not actually indicating notes to be played, but, like Number TAB, is only showing fingerings for the Native American style flute.

If you look closely at the TAB that looks like music above, you will discover there is a note on every line and space between the root and the octave, except for the lines between 1 and 3, or 5 and 6. Those are the missing 2 and 6 that are not part of a pentatonic minor scale!