1 MOA = ~0.291 MIL
1 MIL = ~3.44 MOA
There are 2*pi radian in a circle = 2* 3.14159 = ~6.2832 radians = ~6283.185 milliradians
There are 360 degrees in a circle and 60 minutes per degree: 360 * 60 = 21,600 minutes
6283.185 milliradians/21,600 minutes = 0.29088 mils per 1 MOA
21,600 minutes / 6,283.185 milliradians = 3.43775 MOA per 1 mil