Question

an average mattress contains 2,000,000 dust mites. dust mites are 0.0042 mm in length. what is the scientific notation for each of these numbers?

Answer 1

An average mattress contains 2,000,000 dust mites,

To write the scientific notation of the figure, we must move the decimal point to the left to give

$2,000,000\Rightarrow2\times10^6\text{ dust mites}$

Dust mites are 0.0042mm in length

To write the scientific notation of the figure, we must move the decimal point to the right until we get a significant figure, which gives

$0.0042\Rightarrow4.2\times10^{-3}\operatorname{mm}$

Hence, the right option is C