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function transformB($num){
$res = "";
if($num < 1024){
$res = round($num,2).'B';
}else if($num < 1048576){
$res = round($num/1024,2).'K';
}else if($num < 1073741824){
$res = round($num/1048576,2).'M';
}else {
$res = round($num/1073741824,2).'G';
}
return $res;
}