Question

complete the following subtraction using significant figures. 5.55555 x 10^5 μg - 5.55 x 10^5 μg = what criteria do we use to round off ? significant figures uncertainty

Explanation:

Step1: Factor out $10^{5}\ \mu g$

$(5.55555 - 5.55)\times10^{5}\ \mu g$

Step2: Perform subtraction

$0.00555\times10^{5}\ \mu g$

Step3: Convert to scientific - notation

$5.55\times10^{2}\ \mu g$. When subtracting, we look at the decimal - place of the least precise number. Here, $5.55\times 10^{5}$ is precise to the hundredths place in the decimal part of the coefficient. So our result should also be reported to the hundredths place in the decimal part of the coefficient after the subtraction operation.
For the rounding - off criteria question, when subtracting measurements, we use significant figures for rounding off.

Answer:

$5.55\times10^{2}\ \mu g$
A. significant figures