Hi,
I use the HP 12C at work and own a few of them.
I purchased one that starts with the serial number 21 which I understand means it was made in 1981.
Would you guys agree that this means it was made in 1981?
Also, what is the value of it?
You are right about the serial number interpretation.
(see here)
For units produced between 1981 and 1989,
well preserved units can be had for less than $50 USD
and new old stock units (box, book, inserts, etc)
is frequently available for less than $100 USD.
edit: add serial number link
Edited: 6 Aug 2013, 10:29 a.m.