Answer
(a) and (d)
Work Step by Step
(a) Both numbers have 3 SFs.
- All zeros to the left of the first nonzero digit (5) are not significant.
(b) 405 has 3 SFs, whereas 405.0 has 4 SFs.
- If there is a decimal point, all zeros to the right of the last nonzero digit are significant.
(c) 150 000 has 2 SFs, whereas $1.50 \times 10^4$ has 3 SFs.
- If there is no decimal point, all zeros to the right of the last nonzero digit are not significant.
(d) Both numbers have 2 significant figures.
- If there is a decimal point, all zeros to the right of the last nonzero digit are significant.
