How to correct to 3 significant figures to these values
a)20.961
b)0.275
c)15.62 and 3.555

The significant figures of a number are digits that carry meaning contributing to its measurement resolution. The correct 3significant figures to these values would be 

a)20.961 = 21.0
b)0.275 = 0.275
c)15.62 = 15.6
d) 3.555 = 3.56

Hello!
your answer should be c