Context: CREATE TABLE table_name_21 (number_of_electorates__2009_ INTEGER, constituency_number VARCHAR, district VARCHAR, reserved_for___sc___st__none_ VARCHAR)
Question: What is the number of electorates (2009) for the Indore district, when reserved for (SC / ST /None) is none, and constituency number is 208?
Answer: SELECT SUM(number_of_electorates__2009_) FROM table_name_21 WHERE district = "indore" AND reserved_for___sc___st__none_ = "none" AND constituency_number = "208"