NAVEX, student doing map reading and instructor flying. Flying helo with compass with markings every 5 degrees. Student gets position fix, about 1/2 mile left of track. He wants to impress instructor with his accuracy, does quick mental calculation to reintercept course in 30 nm.
STUDENT: Sir, turn right 1 degree to 243.
INSTRUCTOR: Don't be stupid bloggs, you can't read the compass to 1 degree, how can you expect me to make a 1 degree heading change. Give me decent heading corrections.
STUDENT: Right sir. Turn right 10 degrees to 252.
INSTRUCTOR: That's much better bloggs, well done.
STUDENT: Thank you sir, now turn left 9 degrees to 243.
INSTRUCTOR: Humphh!