GetFormattedFileSize

        public static string GetFormattedFileSize(long totalSizeBytes,Action<string,double> outputAction) {

            double totalSizeKB = totalSizeBytes / 1024D;
            double totalSizeMB = totalSizeKB / 1024D;
            double totalSizeGB = totalSizeMB / 1024D;

            string sizeFormatted = string.Format("{0:N2} KB",totalSizeKB);
            if(totalSizeKB > 1000 && totalSizeMB < 1000)
                sizeFormatted = string.Format("{0:N2} MB",totalSizeMB);
            else if(totalSizeMB > 1000)
                sizeFormatted = string.Format("{0:N2} GB",totalSizeGB);

            outputAction("Bytes",totalSizeBytes);
            outputAction("KB",totalSizeKB);
            outputAction("MB",totalSizeMB);
            outputAction("GB",totalSizeGB);

            return sizeFormatted;
        }