ad esempio

if ($size >= 10**9) { # giga
$size_arr = sprintf("%.2f", $size / 10**9);
}
elsif ($size >= 10**6) { #Mega
$size_arr = sprintf("%.2f", $size / 10**6);
}
elsif ($size >= 1000) { #Kilo
$size_arr = sprintf("%.2f", $size / 1000);
}
else { #byte
$size_arr = $size;
}