Out of the numbers: 6.26, 5.8, 0.00267, 0.03, the one with the least significant figures is:
5.8
6.26
0.03
0.00267
6.26 has 3 significant figures, 5.8 has 2 significant figures, 0.00267 has 3 significant figures and 0.03 has 1 significant figure.