I bought my last useful pocket calculator in 1975 and I still use it regularly. Every time I pick it up I know how to use it, since all the functions I need are printed on its buttons, and I expect to be using it when I retire, if I can still get the batteries. My son bought a “more sophisticated” calculator for his A-levels in 1988 and I inherited it shortly thereafter, it lies in my desk drawer but I cannot use it because it offers so much more than I need and there is too much printed on and around each button. I would need to read the manual every time I wanted to use it. On the desktop close by sits my telephone: It has 46 buttons and a 17-page manual and offers an enticing array of facilities. Unfortunately I only need each of these “facilities” about once a month and have never been able to memorize the necessary procedures. As a result all I can do is answer it when it rings and dial out.