Solve for m E=mc^2 for m

$E = m c^{2}$ for $m$

Rewrite the equation as $m c^{2} = E$ .

$m c^{2} = E$

Divide each term in $m c^{2} = E$ by $c^{2}$ and simplify.

Divide each term in $m c^{2} = E$ by $c^{2}$ .

$\frac{m c^{2}}{c^{2}} = \frac{E}{c^{2}}$

Simplify the left side.

Cancel the common factor of $c^{2}$ .

Cancel the common factor.

$\frac{m c^{2}}{c^{2}} = \frac{E}{c^{2}}$

Divide $m$ by $1$ .

$m = \frac{E}{c^{2}}$