CREATE TABLE table_2383 ("\\u2116" FLOAT, "#" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT, "U.S. viewers  ( millions ) " TEXT)

How many directors for #15?
SELECT COUNT("Directed by") FROM table_2383 WHERE "#" = '15'
SELECT COUNT("Directed by") FROM "table_2383" WHERE "#" = '15'