I noticed there's an FX 991ex emulator you can download on the CASIO web site. I though I'd have a play around with it before deciding if I want one but I failed to get past their incredible software licensing system.
I figured it out. The trick is to ignore all the on-screen instructions and press 'cancel' when it asks you for the license code.
If you mean binary to hex conversions and back, those you can do in your head indeed: peanuts. But I'm not that good when converting say 24 bits binary to decimal Currently I use the windows calculator for that.
To be fair, that would be one of the reasons I'd buy one, too.
But...I played with the emulator and seems like they managed to make it annoying. Not at all easy to use like Windows calculator.
To convert a number you select your mode, type in a number,
press '=', then press a number-base button to convert it.
Yes, it's only one extra button but why can't I just press the number-base button without typing '=' first, like on Windows calculator? So near, yet so far away...
I guess my venerable HP 20S lives another day.
PS: Yes, the calculator accepts "sin(45" without a closing bracket.