Answer
$8.63 \times 10^{-5}$
Work Step by Step
First, count the number of zeros between the first non-zero digit and the decimal point (4). Now include the first digit to get 5 and move the decimal point to the right 5 places.
000008.63
Multiply this number by 10 to the negative power of 5.
$8.63 \times 10^{-5}$
