Determining the Number of Significant Figures in a Measurement

How many significant figures are in each of the following numbers (assume that each number is a measured quantity)? (a) 4.003, (b) 6.023 × 1023, (c) 5000.

How many significant figures are in each of the following measurements? (a) 3.549 g, (b) 2.3 × 104 cm, (c) 0.00134 m3.