This is a common browser glitch. Ensure you are pressing after typing the number, not just clicking outside the box. If the problem persists, refresh the page. Math Playground auto-saves your progress on each level.
For a visual walkthrough of all 32 levels, including the final boss fight, you can watch this gameplay guide: Low's Adventures 2 Walkthrough LogixGenic YouTube• Dec 19, 2023 🏁 Final Boss
Have you beaten all 30 levels? Share your high-score star count in the comments on the Math Playground forums.