Idaho Roy, first the easy part. The Dwyer Wind Meter I mentioned can be seen at
selling for $22 and $15. Just hold their back side into the wind and read the speed next to the floating foam ball. Hold your fore finger over the top for high winds. Such a deal.
"Magic numbers" are the number you use at each range for each load (bullet at some muzzle velocity). Each one has to be calculated then memorized or written on a label taped to the back of the wind meter (that's how I used them). Multiply range in hundreds by wind speed in mph, then divide that answer by the range's magic number.
Example: You've calculated magic numbers for a given bullet as follows:
200 yards = 18
300 yards = 17
and when you get out to the longest range you'll use...
1100 yards = 11
1200 yards = 10
"Magic numbers" can be also called a "wind constant" for a given bullet at a given muzzle velocity at a given range. As range increases, the wind constant gets smaller as wind drift increases in moa.
Let's say the wind's 14 mph from 2 o'clock and your $5 laser rangefinder says the coyote's 850 yards away. Multiplying 8.5 times the 14 mph wind speed is about 120; dividing 120 by your load's 900 yard magic number of 13 you get 9.2. A 2 o'clock wind is worth 90 percent and 90% of 9.2 is about 8.3. So move your sight 8.3 moa into the wind and nail that prairie puppy pouncer pronto!!!
The wind's value from some angle is based on the sine of the angle. At 1 o'clock, the sine of 30 degrees is .5, at 1:30 or a 45 degree wind, the sine is .7, at 2 o'clock, the sine of 60 degrees is about .9 and at 3 o'clock the sine of 90 degrees is 1; a 3 o'clock wind is a full value wind. Same numbers apply from other clock numbers that have the same relative angle.
Hope this helps.