Mental Math for Pilots Practice Test 2026 – Complete Exam Prep Resource

The reciprocal heading is always 180 degrees opposite your current heading. When the initial heading is less than 180, you simply add 180 to get the reciprocal, keeping the result between 0 and 360 degrees. For example, an initial heading of 90 degrees yields a reciprocal of 270 degrees, and 170 degrees yields 350 degrees. The form that adds 200 and then subtracts 20 is just another way to express adding 180 (since 200 − 20 = 180), so it gives the same reciprocal as adding 180 directly. Forms that subtract 180 would require extra wrap-around steps and aren’t the straightforward method here.