CREATE TABLE "table1_2400842_1" (
  "episode_num" real,
  "prod_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "originalairdate" text,
  "filmed" text
);

Question: How many episodes have the title "a perfect crime"?
SQL: SELECT COUNT("episode_num") FROM "table1_2400842_1" WHERE "title"='\"A Perfect Crime\"';

Question: Who directed the epsiode with production number 109?
SQL: SELECT "directed_by" FROM "table1_2400842_1" WHERE "prod_num"=109;