Let $$x = 0.636363\cdots$$  Multiply by $$100$$, which means move the decimal point two places to the right: $$100x = 63.636363\cdots$$  $$x$$ and $$100x$$ have exactly the same decimal part, so if we subtract, it will disappear: $$100x - x = 63.636363\cdots - 0.636363\cdots$$  Which is: $$99x = 63$$ ,$x=\dfrac{63}{99}=\dfrac{7}{11}$  So there is our answer： $$0.636363\cdots=$$$\dfrac{7}{11}$ 
Express $$0.\dot{6}\dot{3}$$ as a fraction. 
(1) $\dfrac{7}{11}$ 
(2) $\dfrac{57}{90}$ 
(3) $\dfrac{636}{1000}$ 
(4) $\dfrac{63}{100}$ 