CREATE TABLE "table1_22589363_2" (
  "series_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real
);

Question: How many series numbers belong to the episode "Vexation of Spirit"? 
SQL: SELECT COUNT("series_num") FROM "table1_22589363_2" WHERE "title"='\"Vexation of Spirit\"';