my @numbers = qw(76.8 77.0 77.2 77.4 77.6 77.8  78.0  
				78.2 78.4 78.6  78.8 79.0 79.2 79.4 
				79.6 79.8 80.0  80.2  80.5 80.7 80.9 81.1);
 
my @small = qw(78.6  78.8 79.0 80.9 77.0);


$s{$_}++ for @small;

@ordered_small = grep { exists $s{$_} } @numbers;

# demo code below:
print "@ordered_small\n";

@numbers = reverse @numbers; 

@ordered_small = grep { exists $s{$_} } @numbers;

print "@ordered_small\n";