ConvertToBinary

public static string ConvertToBinary(ulong value)
{
  if(value==0)
  {
    return "0";
  }
  StringBuilder b = new StringBuilder();

  while(value!=0)
  {
    b.Insert(0,((value&1)==1) ? '1' : '0');
    value>>=1;
  }
  return b.ToString();
}