Question

Can someone explain this please?

Answer 1

$\left( 8 \times 10^{-5}\right)\cdot \left( 5 \times 10^{-6}\right)\\ \\ =\left( 8 \times 5\right)\cdot \left( 10^{-5} \times 10^{-6}\right)$

1) first do the integer part $\left( 8 \times 5\right)=40$ 

2) then do the exponent part $\left( 10^{-5} \times 10^{-6}\right)$ = ???

3) Once you  do the first two steps...  adjust your answer to scientific notation...