Evaluating Expressions Question 10

Which of the following expressions represents the sum of $3.8\times 10^5$ and $6.4\times 10^4$ in scientific notation?

1.02\times 10^{10}

4.44\times 10^4

4.44\times 10^5

10.2\times 10^{20}

44.4\times 10^4

Approach 1

3.8\times 10^5 + 6.4\times 10^4

=38 \times 10^4 + 6.4\times 10^4

=(38+6.4)\times 10^4

=44.4 \times 10^4

=\boxed{4.44\times 10^5}

Approach 2

This question can be easily solved with a calculator.