Colour band $A$ and $B$ indicate the first two significant figures of resistance in "ohm" , while the $C$ band gives the decimal multiplier i.e., the number of zeros that follows the two significant figures $A$ and $B$.

The last band $D$ indicates the tolerance in percentage about the indicate value or in another ward it represents the percentage accuracy of the indicated value. 

As per color coding of a carbon resistor

Color and its values are

$\begin{array}{cc}\mathrm{R}\mathrm{e}\mathrm{d}& 2\end{array}$

$\begin{array}{cc}\mathrm{V}\mathrm{i}\mathrm{o}\mathrm{l}\mathrm{e}\mathrm{t}& 7\end{array}$

$\begin{array}{cc}\mathrm{O}\mathrm{r}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}& 3\end{array}$

$\begin{array}{cc}\mathrm{S}\mathrm{i}\mathrm{l}\mathrm{v}\mathrm{e}\mathrm{r}& 10\%\end{array}$

$\therefore R=27\times {10}^3\pm 10\%$