$ cat x.pl
#!/usr/bin/perl -Tw
use strict;
use warnings;

my $x = "016";
my $y=$x * 10;
print "y=$y\n";

$y = eval( "$x * 10" );
print "string eval evalled 016 * 10 , y = $y\n";

$y = eval { $x * 10; };
print "block eval evalled 016 * 10 , y = $y\n";

$ ./x.pl 
y=160
string eval evalled 016 * 10 , y = 140
block eval evalled 016 * 10 , y = 160