Speed of HP-15C LE - and it's capabilities

[Jeff_Kearns]

I am always amazed at the incredible ingenuity of current and former forum contributors in solving puzzles and mini-challenges, and the various programming techniques used. I would like to tackle the various problems in the Project Euler website one day to see if the HP-15C can handle them all.

I finally got around to entering Valentin Albillo's 160 line program to solve Karl Schneider's A modest arithmetical challenge, posted in April 2007. A worthwhile thread to re-read.

The puzzle involved finding integers from 1 through 9, used exactly once to form three quotients of single-digit integer numerators and two-digit integer denominators, such that the sum of these three terms equals unity. There is only one solution.

The program takes 'a mere' 48 minutes on a physical HP-15C. According to Valentin, a 750x emulator would run this program in less than 4 seconds. So I tried it on the HP-15C LE just now. ... Time: ~20 seconds!!! That is more like 144 times as fast as regular 15C. I am very happy with this calculator, in spite of its bugs, and I regret selling my spare unit last year for a measly $150 (but at least it was sold to a friend who felt he got a good deal) considering what they are going for now, and especially since my 10 year old son is eyeing mine!

Jeff K