Factorial

Score: 49.12 (pass)

#!perl -l
($z=$z*$_%1E6)=~s/0*$//for++$z..pop;print$z%10

Score: 53.12 (pass)

#!perl -l
$_=1;for$z(1..pop){$_=$_*$z%1E6;s/0*$//}print$_%10

Score: 55.12 (pass)

#!perl -l
$_=1;for$z(1..pop){$_*=$z;s/0*$//;$_%=1E6}print$_%10

Score: 64.10 (pass)

#!perl -l
$z=1;map{$z*=$_;$z=~s/.*?(.{1,6}?)0*$/$1/}1..pop;print chop$z

Score: 73.14 (pass)

#!perl -l
$a=1;$a=~s/^.*?(.{0,5}[^0])0*$/$1/,$a*=$_ for 1..pop;print$a=~/(.)0*$/