Total Commander and Ghost Commander on Android solve the problem of two panels in the portrait orientation by displaying one of them and having a button to swit

Total Commander and Ghost Commander on Android solve the problem of two panels in the portrait orientation by displaying one of them and having a button to switch to the other one. However, seeing as some of the success of this calculator app is probably attributed to the ‘memory’ function being non-obvious to people, I'd guess that a hidden calculator might also put some off.