Answer
$1~MeV/c^2 = 1.78\times 10^{-30}~kg$
Work Step by Step
We can convert $1~MeV/c^2$ to units of $kg$:
$1~MeV/c^2\times \frac{1.60\times 10^{-13}~J}{1~MeV}\times \frac{c^2}{(3.0\times 10^8~m/s)^2} = 1.78\times 10^{-30}~kg$
Therefore:
$1~MeV/c^2 = 1.78\times 10^{-30}~kg$
