I hope this is the right place for this... Well, I have a lab where we measured the charge/mass ratio of an electron using a helmholtz coil and vacuum tube. I need to calculate the propagation of uncertainty in my final value. The formula for calculating the e/m ratio is the following... e/m = (2.47E12(a^2/N^2))*(V/((I^2)*r^2))), where a is the radius of the coil that produces the B-field, N is the number of turns in the coil, V is the electron accelerating voltage, I is the coil current, and r is the radius of curvature of the electron beam. Now, when I calculate the propagation of uncertainty the factor 2.47E12 makes the uncertainty very large and the percent uncertainty is around 50%. What do I do about that huge number?? Thanks.