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_204_828 ( id number, "whitworth size (in)" number, "core diameter (in)" number, "threads per inch" number, "pitch (in)" number, "tapping drill size" text )

### Question ###
what is the core diameter of the first 1/8 whitworth size -lrb- in -rrb- ?

### Accurate SQL ###

SELECT "core diameter (in)" FROM table_204_828 WHERE "whitworth size (in)" = '1/8'