scientific notation is
(number >1 and <10) times 10^x
so if you have 4.5 times 10^3 that means
4.5 times 1000=move the decimal place down 3 places
4500 so
0.001
it needs to be 1 times 10^x power
count the decimal places
3 places to the right
when you need to move the decimal place to the right, you multiply it by -x
so 1 times 10^-3 is the answer
