This is not a test of arithmetic. Nothing here needs a calculator. What it asks is whether you can look at a solid and see which flat triangle is hiding inside it — and which rule that triangle is waiting for.
Tap three points. The triangle they make comes out flat. Pick the rule that fits it.
Nothing. No points, no streak. Just the length, and knowing how you got it.
Moves are counted. There is always a shortest route — finding it is the game.