#### Answer

$8.5*10^{-6}$

#### Work Step by Step

To solve this problem, perform the mathematical steps indicated by plugging them into a calculator. Once you obtain this answer, decide the number of significant digits. The number of significant digits is given by the fewest number of significant digits of any of the numbers used. Thus:
.0000085
To convert to scientific notation, move the decimal to the right or left, counting the number of times that you do so, until you get a number that is at least 1 but that is less than 10. If you moved the decimal right, the number of times the decimal is moved will be negative, while moving left yields a positive number. Then, raise 10 to that number. This gives:
$8.5*10^{-6}$