You can leave the TI graphing calculator at home thanks to this web-based TI-83 and TI-84 emulator. As with pretty much all emulators, this depends on a ROM image from the actual hardware to work. But if you have one of the supported calculators (TI-83+, TI-83+ SE, TI-84+, or TI-84+SE) you can dump the image yourself and this should work like a charm.
We’ve seen some arguments online about the price of the TI line over the years. Prices haven’t dropped much over the decades even though they’re making pretty much the same hardware. It’s cool to see someone figure out how to emulate the hardware — and on a web interface to boot! But we’re left wondering why TI isn’t selling an equivalent app for iOS and Android or at least leveraging what must be millions in each production run for a lower retail price?