How to find size of an array in Perl and what are the ways to find it?

Method1:
@a=(1,2,9,5,6);
print scalar @arr;


Method2:
@a=(1,2,9,5,6);
print $#a;   
print $#a + 1;


Method3:
perl -le '@a=(1,2,9,5,6); print $#a + 1;'


Method4:
my $size = @arr;
print $size;


Method 5:
@a=(1,2,9,5,6);
print @a."\n";


Method 6:
@a=(1,2,9,5,6);
print scalar grep /$_/ ,@a;



Method 7:
@a=(1,2,9,5,6);
print scalar map /$_/ ,@a;


Method 8:

@a=(1,2,9,5,6);
print scalar map $_ =~ s///,@a;


Method 9:

@a=(1,2,9,5,6,8);
print scalar grep $_ =~ s///,@a;

Method 10:

@a=(1,2,9,5,6,8);
print $_= map{$_ =~ s///}@a;

Method 11:

@a=(1,2,9,5,6,8);
print  scalar grep{$_ =~ s///}@a;


Method 12:

@a=(1,2,9,5,6,8);
$b=0;
$b+=$_=~s/// for @a;
print $b;