It’s only during the ACT math test that students can use a calculator. Most 4-function, scientific, or graphing calculators are allowed, with some exceptions. If your calculator needs batteries, replace them just before the test; no one wants to spend precious testing time changing out the batteries, and besides, causing any kind of disruption during the test could get a student removed from the premises. And just like bringing extra pencils, bringing an extra calculator is a good idea, too. Even though all of the questions can be answered without one, if you’re used to doing the calculations on a device, you’ll want a backup just in case. To suddenly have to complete the full math section without one can shake your confidence.
The ACT company does publish a list of acceptable calculator brands and models, so it’s a good idea to check it before selecting a calculator. Students are advised to practice with the calculator they plan on using for the test so that they’re comfortable with it. It’s also important to make sure you have your own calculator, as sharing calculators isn’t allowed.