- Analyze (I) 161 cm: According to the rule, all non-zero digits are significant. The digits 1, 6, and 1 are all non-zero.
- Significant figures = 3 [Class 11 Physics, Ch 1, Sec 1.3, Rule 1].
- Analyze (II) 0.0161: For a number less than 1, the zero(s) on the right of the decimal point but to the left of the first non-zero digit are not significant. Therefore, the leading zeros are placeholders. The significant digits are 1, 6, and 1.
- Significant figures = 3 [Class 11 Physics, Ch 1, Sec 1.3, Rule 3].
- Analyze (III) 1.61: All non-zero digits are significant. The digits 1, 6, and 1 are significant.
- Significant figures = 3 [Class 11 Physics, Ch 1, Sec 1.3, Rule 1].
Conclusion: The number of significant figures are 3, 3, and 3 respectively.