Question 1.CC.4: Measured Numbers and Significant Figures Identify each of th......
Measured Numbers and Significant Figures
Identify each of the following numbers as measured or exact, and give the number of significant figures in each of the measured numbers:
a. 42.2 g b. three eggs c. 5.0\times10^{-3}\,{\mathrm{cm}}
d. 450 000 km e. The value of 12 in. for 1 ft = 12 in.
a. The value 42.2 g is a measured number, which has three SFs because all nonzero digits are significant.
b. The value three eggs is obtained by counting, which makes it an exact number.
c. The value 5.0\times10^{-3}\,{\mathrm{cm}} is a measured number, which has two SFs because all numbers in the coefficient of a number written in scientific notation are significant.
d. The value 450 000 km is a measured number, which has two SFs because the zeros in a large number without a decimal point are not significant.
e. The value 12 in. is exact because the relationship 1 ft = 12 in. is a definition in the U.S. system of measurement.