How many series numbers belong to the episode 'Vexation of Spirit'?
CREATE TABLE table_2645 (
    "Series #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" real
)
SELECT COUNT("Series #") FROM table_2645 WHERE "Title" = 'Vexation of Spirit'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many series numbers belong to the episode 'Vexation of Spirit'? ### Input: CREATE TABLE table_2645 (
    "Series #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" real
) ### Response: SELECT COUNT("Series #") FROM table_2645 WHERE "Title" = 'Vexation of Spirit'