you can:
use integer;
it is explained by Michael Ratanapintha or else use manually:
$a=3.7;
$b=2.1;
$c=int(int($a)/int($b));
notice, 'int' is not casting. this is function for converting number to integer form. this is because Perl 5 does not have separate integer division. exception is when you 'use integer'. Then you will lose real division.