What is the series number for the episode number 10 of the season?
CREATE TABLE "table1_27833469_1" (
  "series_num" real,
  "season_num" text,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_millions" text
);
SELECT "series_num" FROM "table1_27833469_1" WHERE "season_num"='10';