Byte轉換為 Kb Mb Gb

private void button1_Click(object sender, EventArgs e)
        {
            textBox2.Text = ByteConvert(Int64.Parse(textBox1.Text));
        }

       
        const int GB = 1024 * 1024 * 1024;
        const int MB = 1024 * 1024;
        const int KB = 1024;

        public string ByteConvert (Int64 InputSize)
        {
            if (InputSize / GB >= 1)
            {
                return (Math.Round(InputSize / (float)GB, 2)).ToString() + "GB"; //Round 函數：四捨五入，(double value傳入值, int digits取幾位)
            }
            else if (InputSize / MB >= 1)
            {
                return (Math.Round(InputSize / (float)MB, 2)).ToString() + "MB";
            }
            else if (InputSize /KB >=1)
            {
                return (Math.Round(InputSize / (float)KB, 2)).ToString() + "KB";
            }
            else
            {
                return InputSize.ToString() + "Byte";
            }
        }