Sig figs

I was reading a problem my brother was assigned in his introductory physics course. The problem specifically asks to give the velocity from viewing a graph. The velocity is 2/3 m/s and it asked to give it in two significant figures. So I thought it would be .66, however the online site he was doing it on said this was incorrect and said the answer was 0.6. I do not agree with this since I was always led to believe the 0 is not a significant figure. Am I incorrect to say that the answer is .66 for two sig figs? I think they just made a mistake. Or am I missing something?



Thanks for reading