Using Standard Form

Question 1:

9.9 \times 10^{-6} + 5.3 \times 10^{-4}

5.399 \times 10^{-4}

Question 2:

6.6 \times 10^{5} - 7.1 \times 10^{4}

5.89 \times 10^{5}

Question 3:

8.3 \times 10^{5} \times 4.7 \times 10^{-6}

3.901 \times 10^{0}

Question 4:

\frac{7.1 \times 10^{6}}{3.9 \times 10^{-3}}

1.82 \times 10^{9}