If the choices are fractions, switch Desmos to fraction form before you compare. A long decimal will not match 5/8 by eye. The calculator is covered in Desmos on the ACT.
Use the fraction button
After you evaluate, click the fraction toggle on the result instead of copying a decimal into the choices. 0.625 is 5/8. 0.333... is 1/3, not “about 0.3.” Fraction and ratio work by hand is in fractions and ratios.
If you already solved on paper, this is a check, not a new start. That habit is in using Desmos to check.
Do not round your way into the wrong choice
Two choices can share the same first digits. Match the exact fraction. Tables that produce those values are in Desmos tables.
The bottom line
When the answer choices are fractions, show the result as a fraction before you select anything.
Start practicing
Start with a free diagnostic, then drill your weak spots with 15-question quizzes and track how you're doing across Reading, English, and Math. Compare plans whenever you're ready to go further.
This article offers general ACT prep guidance. The ACT can change from year to year, including its format, scoring, policies, test dates, and fees, so always confirm the latest details on the official ACT website at act.org before you make decisions. ACT® is a registered trademark of ACT, Inc. thirty-six is not affiliated with, endorsed by, or sponsored by ACT.