Office Hours

Step 1: Spend hours working on a single math problem which makes senses, but seems impossible to solve using the hints given on the assignment.
Step 2: Go to your professors office hours, only to have him point out a single error in the problem as it is written. As a purely hypothetical example, "dot product with y" instead of "dot product with b".
Step 3: Figure out the problem in your head in the next 15 seconds sitting in his office.

You have no idea how common this scheme has become this semester.