CREATE TABLE table_23549 ("#" TEXT, "Original title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original airdate" TEXT, "Prod. code" TEXT)

How many numbers have the product code of 2.6?
SELECT "#" FROM table_23549 WHERE "Prod. code" = '2.6'
SELECT "#" FROM "table_23549" WHERE "Prod. code" = '2.6'