Answer
$8.261\times10^{7}$ (4 sig-figs)
Work Step by Step
$[(285.3\times10^{5})-(1.200\times10^{3})]\times2.8954$
Start with operation in brackets:
$[(285.3\times10^{5})-(1.200\times10^{3})]\times2.8954$
=$[285.3\times10^{5}]\times2.8954$
Since we subtracted, we are allowed to keep as many sigfigs as there were on the lowest figure after the decimal point. 285.3= 1sigfig.
Multiply, use the number with least TOTAL digits for sig figs:
$[285.3\times10^{5}]\times2.8954$
=$8.261\times10^{7}$
285.3 has 4 digits, therefore our answer must have 4.
