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_27987623_4 (rank_timeslot_ VARCHAR, airdate VARCHAR)

### Question ###
what is the total rank on airdate march 30, 2011?

### Accurate SQL ###

SELECT COUNT(rank_timeslot_) FROM table_27987623_4 WHERE airdate = "March 30, 2011"