This article is from the Piano General Topics FAQ, by Isako Hoshino rmmpfaq@yahoo.com with numerous contributions by others.
Some piano technicians seem to prefer a different system,
which starts with A0 at the bottom and ends with C8 at the
top:
A0 B0 C1 D1 E1 F1 G1 A1 B1 C2 D2 E2 etc.
 
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