When checking graphing-calculator work, I get better results by separating the math from the keystrokes: write the expression first, estimate the shape or sign, then enter it and compare. For students who need a browser-based reference while practicing, TI 84 Calculator Online is here: https://ti84.io/ The useful habit is still the final sanity check; window settings, degree/radian mode, and copied signs cause more mistakes than the calculator itself.