c:\@Work\Perl>perl -wMstrict -le
"my $numind = '345xy';
 if ($numind !~ /^\d+/) { die qq{'$numind' is not a number}; }
 print 'sum is ', 123 + $numind;
"
Argument "345xy" isn't numeric in addition (+) at -e line 1.
sum is 468