Scientific calculators are an amazing invention that take pocket calculators from being merely basic arithmetic machines to being pocket computers that can handle everything from statistics to algebra. That said, there are a few layers of scientific calculators, starting with those aimed at students. This is where Casio is very popular, especially because it uses traditional algebraic notation (VPAM) that follows the written style, rather than the reverse-polish notation (RPN) of TI and others. However, much like retro Casio wristwatches, it appears that these Casio calculators are now being (poorly) faked, as explained by [Another Roof] on YouTube.The advanced fx-991 models are updated every few years, with the letters following the model indicating the year, such as fx-991EX standing for the 2015-released model. This was the model that got purchased online and which turned out to be fake. While the fx-991CW is newer, it changes the entire interface and is rightfully scolded in the video. Arguably this makes it the worst Casio scientific calculator in history.After this run-down of how we got to the current Casio fx-991 model, we question why we don’t just use smartphones with a ‘scientific calculator’ app. The answers are ‘exams’ and ‘less complexity’, along with the tactile experience and how this enables muscle memory. Yet due to the CW model’s issues and disdain for muscle memory, the EX model is recommended by teachers. This then opens the market for knockoffs as Casio wanted everyone to move on to the CW model, and parents are always looking for that bargain deal with school supplies.These fake EX models suffer from a variety of issues, depending on the internals. Some are noticeably slower, have omissions and even outright errors in their firmware that make them unusable for a variety of calculations. This makes it rough for both teachers and parents to find a good Casio scientific calculator, even as Casio has already reverted some of the controversial changes in the CW model in an admission of the problems they have caused.Here’s hoping that Casio fully reverts to the EX-style of UI in its next 991-series calculator and finds a way to curb the spread of bad clones of its currently last good scientific calculator.