28. Simplify the following: (2^6*3^3*5^32*6^12*〖10〗^4)/(〖10〗^2*2*6^8*5^31 )
Ans.
(2^6*3^3*5^32*6^12*〖10〗^4)/(〖10〗^2*2*6^8*5^31 )=2^4*3^3*5*6^4*〖10〗^2=279936000

29. Convert the following to scientific notation: .0000900154
Ans.
9.00154×〖10〗^(-5)

30. Simplify the following:
(8zw^2+z^3 w^4-9z^2 w^2 )-(-5z^4 w^3-9z^2 w^2+7zw^2+z^3 w^4-z^4 w^3 )

Ans.
=5z^4 w^3+z^4 w^3+z^3 w^4-z^3 w^4-9z^2 w^2+9z^2 w^2+8zw^2-7zw^2
=6z^4 w^3+zw^2
=zw^2 (6z^3 w+1)