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public string MapReference
        {
            get
            {
                /*
				10km (2-figure) Grid Reference: SO84 = 380000 Easting 240000 Northing
				1km (4-figure) Grid Reference: NS2468 = 224000 Easting 668000 Northing
				100m (6-figure) Grid Reference: TL123456 = 512300 Easting 245600 Northing
				*/
                double easting = Easting;
                double northing = Northing;

                string bngSquare = GetBngSquare(easting, northing);

                //get the number of complete 500k squares
                int indexNorthing = (int)Math.Floor(northing / 500000);
                int indexEasting = (int)Math.Floor(easting / 500000);

                //reduce E and N by the number of 500k squares
                northing -= indexNorthing * 500000;
                easting -= indexEasting * 500000;

                //reduce by the number of 100k squares within the 500k square.
                indexNorthing = (int)Math.Floor(northing) / 100000;
                indexEasting = (int)Math.Floor(easting) / 100000;

                northing -= indexNorthing * 100000;
                easting -= indexEasting * 100000;

                northing = Math.Round(northing / 100);
                easting = Math.Round(easting / 100);
                return $"{bngSquare}{Math.Round(easting):000}{Math.Round(northing):000}";
            }
        }