i need HELP!!!!??

Question

Calculations Using Scientific Notation
Express your answers in scientific notation.
1. (5.11 x 10^2) - (4.2 x 10^2)
how do you get:
(standard notation)STN = 910
(scientific notation)SCN = 9.1 x 10^2
how do you get this^, im really lost!

Answer 1

5.11 x 10^2 - 4.2 x 10^2
10^2 is a common factor to be 'taken out'.
(5.11 - 4.2)x 10^2
0.91 x 10^2

NB 10^2 - 10 x 10 = 100
Hence 0.91 x 100 = 91.0 (STN)

(5.11 - 4.2)x 10^2
0.91 x 10^2
9..1 x 10^1 (SCN)

STN is just numbers as they would be read in normal daily life.
SCN is a number raised to the power of ten. These numbers must always be written as 'X.Y x 10^z' that is integer, decimal point, integer multiplication sign, number '10' raised to the given power.

In your example 910(STN) = 9.1 x 10^2(SCN)
another example 8357= 8.357 x 10 ^3
another example 0.012 = 1.2 X 10^-2

Scientific notation is a method of manipulating very large/small numbers, without having to write a 'string' of zeroes.