CREATE TABLE table_2589 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT)

What's the season number of the episode with series number 84?
SELECT MIN("No. in season") FROM table_2589 WHERE "No. in series" = '84'
SELECT MIN("No. in season") FROM "table_2589" WHERE "No. in series" = '84'