Chemistry: The Central Science (13th Edition)

$8.261\times10^{7}$ (4 sig-figs)
$[(285.3\times10^{5})-(1.200\times10^{3})]\times2.8954$ 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.