Factorial

Score: 48.12 (pass)

shuffle, rinse, repeat

#!perl -l
$_*=$},/0*$/,$}=$`%1e9for++$}..pop;print$}%10

Score: 50.13 (pass)

first try..

#!perl
(($}%=1e9)*=$_)=~s/0*$//for++$}..pop;print$}%10,$/