Mathematical Madness

Part of a Yr11 Extension 1 maths assignment (Australia). Some questions aren't there; I started at q. 17, and the assignment sheet skipped 7 numbers.
I know for a fact that at least one of those is wrong, but I couldn't be bothered correcting it.

Created using Ball point pens (Black, Blue, Red), Felt-tip pens (Blue, Pink, Green, Red), Pencil (0.9mm Mechanical) and white-out (liquid paper & correction tape).

This took me... several hours? (mostly the working out.)
Hope you enjoy it!