Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_27184 ( "No. in series" real, "No. in season" real, "Title" text, "Directed by" text, "Written by" text, "Original air date" text, "U.S. viewers (millions)" text )

### Question ###
What is the number in the series written by Steve Blackman and had a title of 'Worlds Apart'?

### Accurate SQL ###

SELECT "No. in series" FROM table_27184 WHERE "Written by" = 'Steve Blackman' AND "Title" = 'Worlds Apart'