# How would you calculate the molar mass for Bromine Trioxide?

Molar mass of $B r {O}_{3}$? The molar mass is the sum of the atomic masses, and expressed in grams per mole.
So, $\left(79.9 + 3 \times 16.00\right)$ $g \cdot m o {l}^{-} 1$ $=$ ??
Can you tell me the formal oxidation number of $B r$ in this compound if the oxidation state of $O$ is (as usual) $- I I$?