Given P = 0.0030m, Q = 2.40m, R = 3.000m. Significant figures in P, Q and R are respectively       

Given P = 0.0030m, Q = 2.40m and

R = 3.000m. In P (0.0030) initial zeros after the decimal point are not significant. Therefore, significant figures in P (0.0030) are 2. Similarly in Q (2.40) significant figures are 3 as in this case final zero is significant. In R (3.000) all the zeros are significant hence, in R significant figures are 4 because they come from a measurement