Answer
0.512 MeV
Work Step by Step
The rest energy of the electron is found by using equation 26–7.
$$E=mc^2=(9.11\times10^{-31}kg)(3.00\times10^8m/s)^2=8.20\times10^{-14}J$$
Convert to MeV using the given conversion factor to find a rest mass of 0.512 MeV.
(If we had used more significant figures for the calculation, the answer would have been 0.511 MeV.)