Evaluate each expression, Giving the answer in Scientific notation.

1) 5.3 x 10^4 + 4.7 x 10^4

2) 3.7 x 10^6 - 3.3 x 10^6

3)4.8 x 10^-3 + 6.3 x 10^-3

4)6.6 x 10^-5 - 6.1 x 10^-5