What is 3.5x10^2 x 8.0x10^-2 in scientific notation

Scientific notation is defined as writing a number between 0 to 10 multiplied by a power of 10
3.5 x 10² x 8.0 x 10⁻²
when we solve the equation 
answer - 28 
to write in scientific notation the decimal point should come after the first digit from the right. to bring the decimal point from after digit 8 to after digit 2, we have to move one decimal place to the left. then we get 2.8, to get the value as 28 we have to multiply 2.8 by 10
therefore answer is 
2.8 x 10¹

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.