Question

The respective number of significant figures for the numbers 23.023, 0.0003 and 2.1 × 10^–3 are

(a) 4, 4, 2 

(b) 5, 1, 2

(c) 5, 1, 5 

(d) 5, 5, 2

Answer 1

(b) : (i) All the non-zero digits are significant. 

(ii) All the zeros between two non-zero digits are significant, no matter where the decimal point is, if at all.

 (iii) If the number is less than 1, the zero(s) on the right of decimal point but to the left of the first non-zero digit are not significant. 

(iv) The power of 10 is irrelevant to the determination of significant figures. According to the above rules, 23.023 has 5 significant figures. 0.0003 has 1 significant figures. 2.1 × 10^–3 has 2 significant figures.