Answer
No.
Work Step by Step
We know that
$\frac{2}{3}=0.66666...$
where the "$6$"s repeat indefinitely. Thus, we can say that the two values are not equal:
$\frac{2}{3}\neq 0.666$
Furthermore, the fraction $2/3$ is larger because it has more "$6$"s after the decimal (an infinite number). Thus:
$\frac{2}{3}\ \gt 0.666$
The fraction is greater than $0.666$ by the following amount:
$\frac{2}{3}-0.666\gt0.000666...$
