Excluding the bulls-eyes, the numbers are one through to twenty (twenty numbers in total).
there are 20 numbers on a dart board exculding the the bull and 25
20
20
20 numbers
20
20.
Go to "Why are the dart numbers arranged the way they are".
Around the edge of the dart-board !
20 Numbers on a DartBoard.
20...For Wajs Huh...LOL
The standard dart board does not have alternative odd and even numbers. The dart board is set up to encourage accuracy by penalising poor shooting. An excellent site for the mathematical probabilities is http://www.maa.org/mathland/mathland_5_19.HTML
For a score to count, the tip of the dart must be touching the dart board.