This page is designed to let you practice your in head heading calculation. Under the hood and have to turn to a heading of 215 from 305? Doing the math on the right direction, and calculating the seconds takes some thought. You can practice here. Either use the shortest turn, or the time to turn box. If the numbers were:
350 -> 30
Then you'd enter 40 in the shortest turn, or 33/32 in the time to turn. Press enter for the result. This way you can time yourself.

Currently on heading:
127
Go to heading:
turning
Shortest turn: Time to turn:

3º = 1 second
9ª = 3 seconds
15º = 5 seconds
180º = 1 min = 60 seconds