CREATE TABLE "gallery" (
  "number" real,
  "district" text,
  "size_km" real,
  "population" real,
  "density_hab_km" real,
  "councilman" text,
  "party" text
);

Question: what is the size km² when the density hab/km is 8,321?
SQL: SELECT SUM("size_km") FROM "gallery" WHERE "density_hab_km"='8,321';