Calculator forensics is a term coined up by
Mike Sebastian which seeks to answer the questions of who originally designed a particular calculator's chip set, what features of a particular calculator have been borrowed from earlier designs, and how has calculator technology spread among the manufacturers.
How to calculate
To calculate the forensic result of a particular device, make sure it is in degree mode and calculate the following
arcsin(arccos(arctan(tan(cos(sin(9))))))
The result is close to 9, typically something like 8.99999... or 9.00000...
More info
Please visit
Mike Sebastian's site for a detailed analysis.