CREATE TABLE table_28049 ("Series no." FLOAT, "No. in season" FLOAT, "Title" TEXT, "Written by" TEXT, "Directed by" TEXT, "Original air date" TEXT)

How many directors of episode 55?
SELECT COUNT("Directed by") FROM table_28049 WHERE "Series no." = '55'
SELECT COUNT("Directed by") FROM "table_28049" WHERE "Series no." = '55'