This simple snippet can calculate the time required to download a particular file , and can convert KB(s) into MB(s) and Kb(s).

#!/usr/bin/perl -w
print "Type 1 for checking how much time it will take to download with a specified speed\n";
print "Type 2 to convert KBs into MBs and Kbs\n";
$choice = <STDIN>;
if ($choice == 1)
{
    print "Enter the speed ( in KBps )\n" ;
    $speed = <STDIN>;
    print "Enter the file size of the file to be downloaded (in KBs)\n";
    $size = <STDIN>;
    $time_ = $size / $speed;
    if ($time > 60)
    {
            $time_ = $time_/60; print $time_ ." minutes would be taken to download ".            $size ." KB(s)\n";
    }
    else        
    {
        print $time_ ." seconds would be consumed to download ". $size ." KB(s)\n";
    }
}
else
{
print "Type the amount of KBs\n";
$size2 = <STDIN>;
$MBs = $size2 / 1024 ;
$Kbs = $size2 / 8 ;
print  $MBs ." MBs and ". $Kbs ." Kbs\n" ;
}