I just use the Python interpreter. I can creat sophisticated equations, use variables, change bases, perform unlimited precision arithmmetic, format output, lod int function and libraries to compeute matrices, plot graphs, and more. However, not all of us are Python-literate so a physical calculator emulator is more attractive. As they go in the free segment, this is not bad. Also consider BinCalc for multi-base work and CalcThingy.