CREATE TABLE "table1_224840_4" (
  "district" text,
  "vacator" text,
  "reason_for_change" text,
  "successor" text,
  "date_successor_seated" text
);

Question: How many seats became avaliable in Massachusetts 3rd district?
SQL: SELECT COUNT("vacator") FROM "table1_224840_4" WHERE "district"='Massachusetts 3rd';

Question: Who left office on November 26, 1800?
SQL: SELECT "vacator" FROM "table1_224840_4" WHERE "date_successor_seated"='November 26, 1800';

Question: Who was the latest to take office in Massachusetts 3rd district?
SQL: SELECT "successor" FROM "table1_224840_4" WHERE "district"='Massachusetts 3rd';