The total of the numbers 1 through 20 on a standard darts board is 210.
This comes from adding every numbered segment once: 1 + 2 + 3 through 20. The result is 210, regardless of how the segments are arranged around the board.
That total does not represent a normal darts score. Players score by hitting particular areas, including singles, doubles, trebles, the outer bull and the inner bull. A dart in a treble scores three times the printed number, while a dart in a double scores twice it.
The board’s unusual numbering order is designed to punish inaccurate throwing by placing large numbers beside relatively small ones. The numbers are not arranged sequentially around the circle, so the visual total of all segments is different from the maximum score available in a turn.