Secret Number

Score: 61.00 (pass)

#!/usr/bin/perl -l
$_=pop;print,s/.(?=(.))/$&+$1-($&+$1>9)*9/ge,chop while/./

Score: 68.00 (pass)

#!/usr/bin/perl -l
$_=pop;while(/./){print;s/.(?=(.))/$a-=(($a=$&+$1)>9)*9/ge;chop;}