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_66253 ( "Class" text, "Wheel arrangement" text, "Fleet number(s)" text, "Manufacturer" text, "Serial numbers" text, "Year made" text, "Quantity made" text, "Quantity preserved" text )

### Question ###
What is the quantity preserved for the serial number of mallet and simple articulated locomotives?

### Accurate SQL ###

SELECT "Quantity preserved" FROM table_66253 WHERE "Serial numbers" = 'mallet and simple articulated locomotives'