(20pts) what is the product in scientific notation?
(2.5*10^-8)(9*10^-10)

                     (2.5 x 10⁻⁸) x (9 x 10⁻¹⁰)

                  = (2.5  x  9)  x  (10⁻⁸  x  10⁻¹⁰)

                  =    (22.5)    x      (10⁻¹⁸)

                  =         2.25 x 10⁻¹⁷  .

So remember that exponential rule that is
x^m times x^n=x^(m+n)
also the commutative property which is ab=ba
aso the associattive which is (ab)c=a(bc) so
(2.5*10^-8)(9*10^-10)
associative and commutative to move exponents together
(2.5*9)(10^-8*10^-10)
10^-8 times 10^-10=10^(-8-10)=10^-18
(22.5)(10^-18)
the anaswers should be
(number less than 10 andmore than or equal to 1) times (10^x)
22.5 times 10^-1=2.25
2.25 times 10^1=22.5 so
(2.25 times 10^1)(10^-18)
associative
(2.25)(10^1*10^-18)
(2.25)(10^-17)
answer is 2.25*10^-17