Question

what is 0.003010 as a significant figure

Answer 1

All numbers (not 0) are significant.
So the 3 and the 1 are significant.

Now, zeroes that are between two significant figures are also significant.
So the 0 between the 3 and the 1 is significant.

Trailing zeroes after the decimal point are significant.
So the final 0 after the 1 is significant.

That gives us 2+1+1 = 4 significant figures.