Answer
$$ 3.91\times10^8$$
Work Step by Step
Recall, for a number to be in scientific notation, it must be in the form $a\times 10^b$, where a must be between 1 and 10. Thus, we simplify the expression. If necessary, we change b until the value of a is between 1 and 10. Doing this, we find that the expression becomes:
$$ 3.91\times10^8$$
