Recently I purchased a new calculator because someone pointed out to me the truly amazing capabilities (natural textbook display) of Casio’s new fx-115ES calculator. Costing under €30, the calculator offers an astounding 403 functions, conversions and solvers. It also displays fractions as true fractions, in addition to the standards floating point display format.. It can handle tables for linear or cubic interpolation for which the data entry is pretty easy. It performs numerical differential and integration, and solves equations with Newton-Rapson. It can even do (limited) vector and matrix calculations.

Even though I am a big fan of Texas Instruments integrated circuits (especially  their MSP430  microcontrollers, their ADCs (ADS1178) and power ICs (TPS84620) ) I prefer Casio’s calculators over TI’s. They are not as bulky, you can get your results more quickly and they cost a lot less.

When I got the new calculator , I realised I had purchased the fx-115 before. The first model I got was the fx-115 in 1985, when I was in school. Later, it also served me well as a student at Delft University of Technology.  Looking for a model that would help me with complex numbers, I bought  the fx-115W when I worked at Oresis Communications in 2001. This was my main computational workhorse in the new millennium. And, this year I purchased the amazing fx-115ES. In a way I have been quite intimate with the fx-115 family for 26 years!

All calculators, including the 26 years old fx-115, still work flawlessly, a testimony to Casio’s build quality. Begin solar driven, I never had to replace a battery. The fx-115 now lives in a kitchen drawer and is used for domestic purposes.

My calculators are  (running $sqrt {2} /4$: