There are some problems with your command loop. Normally this question of "are you finished or not?" is a bad idea. Instead of "another Pair of numbers? Y/N?", just prompt for the next pair of numbers like at the first prompt. If I don't have another set of numbers, then I quit, exit, CTL-C or whatever.

I may have goofed up something below, but I did run this code on my machine and it should give you some ideas about the command loop and how to use printf() for this problem.

#!usr/bin/perl -w
use strict;

my $title = "SOME REPORT TITLE";
my $LINES_PER_PAGE =10;

my $page =1;
my $line =9999;

sub get_header_string
{
   "\n$title , Page $page\n".
    " ---------------------------------\n".
    " NUMBER1 || NUMBER2 || ADDITION\n".
    " ---------------------------------\n";
}

while ( (print "Enter a pair of numbers (space between) or quit: "), 
        (my $line =<STDIN>) !~ /^\s*q(uit)?\s*$/i  
      )
{
    next if $line =~ m/^\s*$/;     #re-prompt for blank lines
    
    my ($num1, $num2, $kruft) = split(/\s+/,$line);    
    if (      $kruft             #user input validation is
          || ($num1 =~ m/\D/)    #important, I like this style
          || ($num2 =~ m/\D/)    #of formatting, others like 
        )                        #something different          
    {  print_command_error();  next; }
    
    foreach (1..100)
    {
       output ($num1, $num2, $num1+$num2);
       $num1++; $num2++;
    }    
}

sub print_command_error
{
   print "Illegal command args....\n";
   print "some other message..probably usage message\n";
}

sub output
{
   my ($num1, $num2, $sum) = @_;
   if ($line++ >= $LINES_PER_PAGE)
   {
     if ($page >1) {print "\f"}
     print get_header_string;
     $line = 1; 
     $page++;
   }
   printf ("  %-9d %-10d %-10d\n", $num1, $num2, $sum);
}
__END__
C:\TEMP>useprintf.pl
Enter a pair of numbers (space between) or quit: 1 2

SOME REPORT TITLE , Page 1
 ---------------------------------
 NUMBER1 || NUMBER2 || ADDITION
 ---------------------------------
  1         2          3
  2         3          5
  3         4          7
  4         5          9
  5         6          11
  6         7          13
  7         8          15
  8         9          17
  9         10         19
  10        11         21
\f
SOME REPORT TITLE , Page 2
 ---------------------------------
 NUMBER1 || NUMBER2 || ADDITION
 ---------------------------------
  11        12         23
  12        13         25
  13        14         27
  14        15         29
  15        16         31
  16        17         33
  17        18         35
  18        19         37
  19        20         39
  20        21         41
\f
SOME REPORT TITLE , Page 3
...blah....
[download]

#!usr/bin/perl -w
use strict;

#File Add2Num.pl

my $title = "SOME REPORT TITLE";
my $LINES_PER_PAGE =10;
my $ITERATIONS = 100;

my $page =1;
my $line =9999;

if (@ARGV)
{
   print " Usage: add2nums\n".
         "   No command line args allowed\n".
         "   program will prompt for a range of integers\n";
   exit(-1);
}

sub display_range_error
{
   print "ERROR!\n";
   print "MUST have 2 positive numbers like: 11 23\n";
}

sub page_header
{
   "\n$title , Page $page\n".
    " ---------------------------------\n".
    " NUMBER1 || NUMBER2 || ADDITION\n".
    " ---------------------------------\n";
}

while ( (print "Enter a pair of numbers (space between) or quit: "), 
        (my $line =<STDIN>) !~ /^\s*q(uit)?\s*$/i  
      )
{
    next if $line =~ m/^\s*$/;     #re-prompt for blank lines
    
    my ($num1, $num2, $kruft) = split(/\s+/,$line);    
    if (      $kruft             #user input validation is
          || ($num1 =~ m/\D/)    #important, I like this style
          || ($num2 =~ m/\D/)    #of formatting, others like 
        )                        #something different             
    { display_range_error();  next; }
    
    foreach (1..$ITERATIONS)
    {
       output ($num1, $num2, $num1+$num2);
       $num1++; $num2++;
    }    
}

sub output
{
   my ($num1, $num2, $sum) = @_;
   if ($line++ >= $LINES_PER_PAGE)
   {
     if ($page >1) {print "\f"}
     print page_header;
     $line = 1; 
     $page++;
   }
   printf ("  %-9d %-10d %-10d\n", $num1, $num2, $sum);
}
__END__
C:\TEMP>useprintf.pl
Enter a pair of numbers (space between) or quit: 1 2

SOME REPORT TITLE , Page 1
 ---------------------------------
 NUMBER1 || NUMBER2 || ADDITION
 ---------------------------------
  1         2          3
  2         3          5
  3         4          7
  4         5          9
  5         6          11
  6         7          13
  7         8          15
  8         9          17
  9         10         19
  10        11         21
\f
SOME REPORT TITLE , Page 2
 ---------------------------------
 NUMBER1 || NUMBER2 || ADDITION
 ---------------------------------
  11        12         23
  12        13         25
  13        14         27
  14        15         29
  15        16         31
  16        17         33
  17        18         35
  18        19         37
  19        20         39
  20        21         41
\f
SOME REPORT TITLE , Page 3
[download]