Parallelograms - it helps to hold something up to block the other lines, they throw your eye off. Triangle you need to keep thinking right angle for the closest path to each side, and/or imaging a circle around the point, touching each side.
3.14 by cheating. Command-option+ to zoom the screen in, and a ruler. If you take your time, you can get a lot of ones, even got a zero and a 0.3. Yeah, takes the fun out of it. But I fumbled a few, so 3.14. Probably 3.141592653589793 if they took the decimal out far enough.
I'm guessing the people with the really low scores are using rulers, and taking plenty of time. They should have a timed version.
-ERD50