CREATE TABLE table_29270 ("No. in series" TEXT, "No. in season" TEXT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT, "Production code" TEXT)

How many production codes did the episode number in series 46b have?
SELECT COUNT("Production code") FROM table_29270 WHERE "No. in series" = '46b'
SELECT COUNT("Production code") FROM "table_29270" WHERE "No. in series" = '46b'