Plz help with these questions!!

I feel uncomfortable at having been bamboozled.  You sent me
a message saying you wanted me to "check" your math work. 
Sadly, the truth is that you haven't necessarily tried any of these,
and there's nothing to "check".  What you really want from me is
just the answers.

1).  62,000,000  =  6.2 x 10⁷

2).  -3.05 x 10⁶  =  -3,050,000

3).  0.00000089  =  8.9 x 10⁻⁷

4).  (9.8 x 10²) x (5.9 x 10⁷)  =  (9.8 x 5.9) x (10²⁺⁷) =

                                                      57.82  x    10⁹  =

                                                     5.782  x  10¹⁰ .

5).  (7.2 x 10⁻⁵) / (4.3 x 10⁻³)  =  (7.2 / 4.3) x (10⁻⁵ / 10⁻³) =

                                                       1.67    x  (10⁻⁵ ⁺³)  =

                                                       1.67   x  10⁻² .