Just use br tag, see the script below.

 #!C:\Perl\bin\perl.exe -wT 
use strict; 
use CGI ':standard';

my ($number,$value); 
$number = param('number'); 
$value = param('name');

print "Content-type:text/html",br,br; 
$number = $number + 20; 
print "$value will be $number in twenty years."; 

# separate above operation from below condition 

print br,br; #<------------- Use br 

if ($number >= 40) { 
   print "Wow $value, you're old!"; 
} 
else { 
   print "Wow $value, you're still young!"; 
}
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