Question

How do you write the answer in scientific notation given `(2.1times10^-4)/(8.4times10^-6)`?

Answer 1

`2.5xx10^1`

Explanation:

`(2.1xx10^(-4))/(8.4xx10^(-6))`

`=0.00021/ 0.0000084`

`=2100/ 84`

`=25`

`=2.5 xx10^1`

Answer 2

`2.5 xx 10^1`

Explanation:

Use the exponent rule `x^m/x^n = x^(m-n)`

`(2.1 xx 10^-4)/(8.4 xx 10^-6) = 2.1/8.4 xx 10^(-4- -6) = 0.25 xx 10^2`

Scientific notation requires a non-zero number to be to the left of the decimal point. This means you need to move the decimal to the right one place which decreases the exponent by 1:

`0.25 xx 10^2 = 2.5 xx 10^1`