scientific notation

Simplify the expression. Write the answer in scientific notation. left parenthesis 9 times 10 Superscript negative 4 right parenthesis left parenthesis 6 times 10 Superscript negative 5 right parenthesis(9×10−4)(6×10−5)

$\begin{array}{rcl} (9\cdot 10^{-4}) \cdot (6\cdot 10^{-5}) &=& 9\cdot 10^{-4} \cdot 6\cdot 10^{-5}\\ &=& 9\cdot 6\cdot 10^{-4} \cdot 10^{-5} \\ &=& 9\cdot 6\cdot 10^{-4+(-5)} \\ &=& 9\cdot 6\cdot 10^{-9} \\ &=& 54\cdot 10^{-9} \\ &=& 5.4\cdot 10\cdot 10^{-9} \\ &=& 5.4\cdot 10^1\cdot 10^{-9} \\ &=& 5.4\cdot 10^{1-9} \\ &=& 5.4\cdot 10^{-8} \\ \end{array}$

(9x10^-4) (6 x 10^-5)

=   54 x 10^(-4+-5)

54 x 10 ^-9  = .000000054