Question

Which is the best estimate for (6.3x10^-2)(9.9x10^-3) written in scientific notation?

Answer 1

It should be 6.237*10^-4

Answer 2

Answer:

$6 \times 10^{-4}.$

Step-by-step explanation:

We are given expression $(6.3 \times 10^{-2})(9.9\times 10^{-3})$.

In order to multiply above given expression, we need to multiply 6.3 by 9.9 first.

On multiplying 6.3 by 9.9 , we get 62.37.

Now we would multiply  $10^{-2} \ by \ 10^{-3}.$

Therefore,

$10^{-2} \times 10^{-3}= 10^{-2-3}= 10^{-2-3} = 10^{-5}.$  

Therefore,

$(6.3 \times 10^{-2})(9.9\times 10^{-3}) =62.37 \times 10^{-5}$

Again $62.37 \times 10^{-5}$ could be written as $6.237 \times 10^{-4}$.

Now, $6.237 \times 10^{-4}$ could be round to $6 \times 10^{-4}.$

Therefore, correct answer is  $6 \times 10^{-4}.$