ACT Math

Similar solids on the ACT

October 14, 2026 · 5 min read

Similar solids: lengths scale by k, areas by k², volumes by k³. If k = 2, surface area is 4 times and volume is 8 times. Scale factor as a set is in scale factor.

Power matches the dimension

Linear, then square, then cube. Area and volume as a set are in area and volume. Area of a kite is a different leftover, in area of a kite.

The bottom line

k, k², k³. Do not scale a volume by k².

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.