I would say to pass the aptitude tests and subsequent ATPL exams you would need to have a good grasp of; addition, subtraction, multiplication, division, BIDMAS, ratios, fractions, Algebra(understand how to rearrange formula), SOH CAH TOA, Pythagoras Theorem, area & circumference of circles.
A lot of calculations in aviation exams can be done by rounding the numbers up, i.e. 3643/277 becomes 3600/300. A relevant example of rounding would be working out barometric error in altimeter questions, technically you should use 27ft per millibar, though usually its rounded up to 30ft.
However!!
When it comes to actually flying the plane, you haven't got time for all this academic BS. When you are trying to navigate your little Cessna or Piper VFR through SE England with no autopilot or Skydemon, you haven't time to sit there trying to do fancy equations. The clock face rule that Wiggy has explained above is a really important one to understand and use; in critical stages of flight you should be able to calculate crosswind component quickly.
In real navigation for example, before you get into the a/c you can draw a little compass rose on your plog with N,NE,E,SE,S,SW,W,NW, get your CRP5 and figure out what your drift and groundspeed would be on each of those compass heading, then make a note of it on your plog. Therefore, inflight when your instructor asks you to divert in say a north easterly direction, you already know roughly what your groundspeed and drift is from looking at your plog, then you look at your speed/distance table - bingo you know the ETA and heading to take up.
As you can see, flying is or should be very practical. The maths is really for the ground exams.