Puzzle Solution:
1. Drop the number before you collect the money.
2. Move the camera up so the stone can't be seen.
3. The options menu can block the number.
4. The yellow number won't reset, even if you respawn.
5. Drop the number when the camera moves.
6. Left-click (LMB) on the stone to increase the number.
7. 9 + 1 = 10. The numbers will drop separately and become 0.