This is one of the only calculators on Scratch that actually solves multi-step equations with the order of operations like (3+3*3-3/3)(20-9)-121=0 rather than just 1+1=2 or something like that. It's also by far the nicest looking. Shortcuts (button → keyboard) = → enter CE → \ C → shift + \ × → * ÷ → / If you don't know, C is clear and CE basically means backspace. You can drag the text to see more (for long equations). The rest is straightforward.
Scratch can't handle large numbers very well, so don't say the calculator isn't working because of that. There may be other bugs; I'm still working on that.