$\dfrac{2013.2014......3012}{1.2.3......1000} : \dfrac{1001.1002......3012}{1.2.......2012}$
$= \dfrac{2013.2014......3012}{1.2.3......1000} . \dfrac{1.2.......2012}{1001.1002......3012}$
$= \dfrac{1.2.3......2012.2013.2014.......3012}{1.2.3......1000.10001.1002......3012}$
$= \dfrac{1}{1}$
$= 1$.