... part of the value? first example: v (MHz) = 110 B(nT) E^2 (GeV) could someone confirm that when an equation is like this you simply change E into GeV before squaring it and making the calculation? slightly confused. second example: rest mass of a Pion is stated by Wiki as 139.57018(35) MeV/c^2, why is this? are there units of c^2? what if you want to use the mass in a calculation, do you divide 139MeV by the speed of light squared? not sure what to do with this. Thanks for any help.