I need a standard system to number the notes of the keyboard, especially
for use in mathematical formulae in a spreadsheet.

I propose that the MIDI definition be used, which simply declares:
"MIDI note 60 is defined as Middle C of the piano keyboard."  The MIDI
specification committee, which formulated the MIDI spec in the early
1980s, chose this easy-to-use definition since all 'C's on the keyboard
are numbered as integral multiples of 12.

This short table illustrates how MIDI note numbers relate to the
traditional names for notes:

  n    Hz   Europe   MIDI  open pipe

 12    16.35   ''C    12C  32 ft.
 24    32.7     'C    24C  16 ft.
 36    65.41     C    36C   8 ft.
 48   130.8      c    48C   4 ft.
 60   261.6     c'    60C  (Middle C, keyhole C)
 69   440.0     a'    69A  (standard A=440 Hz)
 72   523.3    c''    72C
 84  1047     c'''    84C
 96  2093    c''''    96C
108  4186   c'''''   108C

The modern piano keyboard with 88 keys spans 21A to 108C.  The 97-key
Boesendorfer adds extra bass keys down to 12C.  The 61-note organ
keyboard ('8-foot') spans 36C to 96C.

MIDI editor/sequencer programs also display octave numbers: Middle C is
the lowest note of octave number 3 in Master Tracks, but octave number
5 in Cakewalk -- there is no standard.  I therefore append the octave
number depending upon which editor I'm referring to: 60C3 with Master
Tracks, 60C5 with Cakewalk.

Hans van Oost wrote a summary which appears at
http://mmd.foxtail.com/Tech/Scales/nomenclatuur_muziek.html

I invite comments from MMD readers.

Robbie Rhodes