[lasagnaphil]

You can get close-enough ballpark answers on the angles between (0, 30, 45, 60, 90). (If the questions are multiple choice, then you can design it in a way that you don't need a calculator) And this is actually quite an important handy skill you will have in real life, since later on when you're drawing graphics/diagrams either on software or hardware you really need that intuition of ball-parking angles.