The Pioneer series was undoubtedly the most diverse series HP ever made..

So, my fellow HP fans, here is a challenge for you:1. Identify each Pioneer model by only the top row of keys. (picture below)

2. Let S be the Sum of the product of row number and model number for each calculator.

For 17bii and 32sii use 17^2 and 32^2.

Voyager Example:

3. SQRT(S)+1 is the year my first (and favorite) HP calculators were made.

4. What are my favorite calculators?

*Edited: 9 Mar 2007, 11:57 p.m. *