use strict;

# for actual use, read from an open file handle line this:
#while (my $line = <$input> {

# for testing, read from special DATA file handle 
# (data will come from end of file, below DATA tag)
while( my $line = <DATA>) {
  chomp $line;            # remove end-of-line character
  $line =~ s/^\s+//;       # strip leading whitespace
  next unless $line;      # skip blank lines
  
  # skip first 12 lines 
  next unless $. > 12;     # $. contains current line number
  
  my @columns = split(/\s+/, $line);    # split columns on whitespace
  
  my $col1 = shift @columns;  # column 1 (throw away)
  my $col2 = shift @columns;  # column 2 (throw away)
  
  my $col3 = shift @columns;  # column 3 (special - keep this one) 
  my $result = sprintf("%8.3f", $col3); # special format for col 3

  # loop over remaining columns, appending to result string
  for my $c (@columns) {
    my $data = sprintf("%10.3f", $c);
    $result .= " $data";                # note the space character (ch
+ange if required)
  }  

  print "$result\n";                    # print the final result (note
+ end of line character)"
}

# my guess at the input data
__DATA__
SKIP 1
SKIP 2
SKIP 3
SKIP 4
SKIP 5
SKIP 6
SKIP 7
SKIP 8
SKIP 9
SKIP 10
SKIP 11
SKIP 12
Line_1 0.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
Line_2 0.0 0.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0
Line_3 0.0 0.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 1.0
Line_4 0.0 0.0 4.0 5.0 6.0 7.0 8.0 9.0 1.0 2.0
Line_5 0.0 0.0 5.0 6.0 7.0 8.0 9.0 1.0 2.0 3.0
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update: fixed typo in "strip whitespace" regex (added '^' character)