Prof Kahan emphasizes the complexity of time-value of money calculations, highlighting the iconic HP-12c financial calculator. The author, initially ignorant of finance, delves into TVM calculations due to personal mortgage and political events. They describe programming their calculator, testing multiple financial calculators, and discovering a rogue variant of the HP-12c in Brazil that returns inaccurate results. The author presents challenging TVM problems and the rogue calculator’s failures and successes, speculating on the origins of the altered TVM solver. The article showcases the intricacies of financial calculators and the pursuit of accuracy in TVM calculations.
https://dm319.github.io/pages/2024_09_09_hp12_comma.html