Fill in the blank.

A dartboard has 20 equally divided wedges, and you are awarded the number of points in the section your dart lands in. If you are equally likely to land in any wedge, what is the probability you will score 21 points?
/20 possible outcomes

The numbers on the board are
20 1 18 4 13 6 10 15 2 17 3 19 7 16 8 11 14 9 12 5