Pilots, I need help.?

Like a previous answer said, most pilots don't really use a ton of formula after flight training. In the airlines, I usually only use math to determine what are called crossing restrictions. Air traffic control will say for example "cross the Falcon VOR at 14,000 ft. If we were at 25,000 ft, there is simple math to figure out when we need to start descending, and at what rate. Take the difference in altitude (25-14=11). Multiply that number by 3, so 33. This means you need to start a descent 33 miles away from the Falcon VOR. The next step is the descent rate. Take the aircraft's groundspeed (the speed of the aircraft over the ground, taking the wind into account) and multiply it by 6. For example, if the groundspeed is 300 knots, 300 x 6= 1800. You need to descend at 1800 feet per min.