The TI-84 Plus graphing calculator is on sale for less than $90

TL;DR: The forever-useful Texas Instruments TI-84 Plus graphing calculator is on sale for $88 at Walmart, saving you $28.

Since the dawn of time (okay, 1990), high school and college algebra classes are known for requiring those damn graphing calculators.

Will you ever use y=mx + b in the real world? That’s debatable.

Will you ever use the good grades you got from opting for a real graphing calculator over a free, crappy app? Definitely.

The Texas Instruments TI-84 Plus are notoriously pricey, but you can grab one on sale for $88 at Walmart with free delivery. (They were $149.99 when I was in school, so be thankful.) Unfortunately, the newer rose gold model is still $118.

Nearly everything you need to do even the most complicated equations is already installed in your TI-84 Plus, including Cabri Jr. interactive geometry software to aid in problems surrounded triangles, circles, line length, and more. You no longer have to do math by hand to calculate things like sin, cos, or tan — there’s a button that does it for you. The LCD screen could definitely use a color HD glow-up, but I guess it keeps things simple.

Keep your equations straight by saving and analyzing up to 10 graphing functions at a time, as well as using the split-screen option to compare answers or tackle a multi-step problem.

Even if you only use it for a year, it’s one of those items that someone always needs and is willing to buy on eBay.

Regularly $116, you can save $26 and get the TI-84 Plus for $88 with free delivery.