CREATE TABLE table_26112 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" CLOB, "Directed by" CLOB, "Written by" CLOB, "Original air date" CLOB, "U.S. viewers  ( millions ) " CLOB)

How many episodes in the series are also episode 18 in the season?
SELECT COUNT("No. in series") FROM table_26112 WHERE "No. in season" = '18'
SELECT COUNT("No. in series") FROM "table_26112" WHERE "No. in season" = '18'