Table: successors_seated
Columns: district
vacator
reason_for_change
successor
date_successor_seated

Question: How many seats became avaliable in Massachusetts 3rd district?
SQL: SELECT COUNT("vacator") FROM successors_seated WHERE "district" = 'Massachusetts 3rd'

Question: Who left office on November 26, 1800?
SQL: SELECT "vacator" FROM successors_seated WHERE "date_successor_seated" = 'November 26, 1800'

Question: Who was the latest to take office in Massachusetts 3rd district?
SQL: SELECT "successor" FROM successors_seated WHERE "district" = 'Massachusetts 3rd'