Question

How many significant figures are present in the following? 
(i) 0.0025 
(ii) 208 
(iii) 5005 
(iv) 126,000 
(v) 500.0 
(vi) 2.0034

Answer 1

Number	Significant Figures	Reason (brief)
(i) 0.0025	2	Leading zeros are not significant; only 2 and 5 count.
(ii) 208	3	All non-zero digits and zeros between them are significant.
(iii) 5005	4	Zeros between non-zero digits are significant.
(iv) 126,000	3	Trailing zeros in a whole number without a decimal are not taken as significant.
(v) 500.0	4	Trailing zero after a decimal point is significant.
(vi) 2.0034	5	All non-zero digits and zeros between non-zero digits are significant.