Well, in the interest of disclosure, I ought to chime in...

45 -- bought my HP-15C new in 1983 after having coveted the HP-41 and HP-34C, but not being able to afford them.

I started collecting in 2002 after seeing and buying the "foregone" HP-34C and and HP-41CV in a local used-electronics store. My collection now includes at least one of each model in three series -- HP-41, Voyager, and Pioneer. My collection represents RPL with the HP-28C, HP-48G, and HP-49G. I also have the HP-71B.

For those who are compiling statistics of this data on an RPN-based HP calc, I'd recommend *not* the HP-21S Stat/Math, which utilizes the summation method for calculation of mean and standard deviation. Instead, I'd use the HP-17B/BII or HP-27S. These models save all input data for sorting, and the calculation of median, minimum, maximum, and range. I believe that all the RPL-based models will do the same.

So far --

responses: 85 (includes Eric Smith's, which is not as obscure as it might seem...) ;-)
median: 46

minimum: 22

maximum: 82

mean: 48.0 (closer to 48.5, if reported ages were not rounded down)

std dev: 11.9 (sample)

I'll post final results and a makeshift histogram when the responses stop coming in...

The average ages are about what I expected, based on previous instances of this topic. The era in which scientific calculators debuted, and later became capable and affordable, coincides with the late youth and young adulthood of the majority of us.

-- KS

*Edited: 19 Feb 2009, 3:18 a.m. *