| Lara- I'm teaching triads in music theory right now!!! How odd of a coincidence is this?
I started writing an explanation, but if I'm not right there with a staff and a piano..well, it could be more confusing than it needs to be.
Those numbers indicate chord inversions. You can use the numbers to harmonize a bass line by simply adding the requestedd number over the note provided. So if you have a bass line and there's a 2nd space C there, below the C yoou have 6-4, then add an A and an F (a 6th and a 4th) above the C.
The other way this is used is to indicate chord inversions (revoicings).
6 (AKA 6-3) is first inversion (the 3rd of the triad sounds the lowest)
6-4 (the fifth sounds lowest)
7th chords can be scary because there are 3 inversions:
6-5(3) (first inversion: 3rd sounds lowest)
4-3 (2nd inversion: 5th sounds lowest)
4-2 (3rd inversion: 7th sounds lowest)
An easy way to see this is to take a C triad and play it on a piano moving the bottom note up an octave each time.
Hope you find that helpful. I am out of time, so I can't really delve too much more...
__________________
-Glenn
"Roses have thorns; shining waters mud. Clouds and eclipses stain the moon and the sun; and history reeks of the wrongs we have done. After today, after today, consider me gone."- Sting |