The value of the integral $\int\limits_0^{0.9}[x-2[x]] d x$, where [.] denotes the greatest integer function, is

0.9 0 1.8 -0.9

0

$\int\limits_0^{0.9}[x-2[x]] d x$ $=\int\limits_0^{0.9}[x-2 \times 0] d x=\int\limits_0^{0.9}[x] d x=\int\limits_0^{0.9} 0 d x=0$