@tectlist = ( [1,5,6,8,16,20],
              [1,7,10,12,13,14,15,18,19,22,23,24,46],
              [1,2,3,9,10,11,17,21,24,39,46],
            );
$variable=19;

for my $i (0..$#tectlist) {
    if (grep {$_ == $variable} @{$tectlist[$i]}){
      my $listnumber = $i+1;
      print "List $listnumber contains $variable.\n";
    }
}