What is the fleet number of the locomotive with 1 quantity made?
CREATE TABLE "1912_1922" (
  "class" text,
  "wheel_arrangement" text,
  "fleet_number_s" text,
  "manufacturer" text,
  "year_made" text,
  "quantity_made" text,
  "quantity_preserved" text,
  "year_s_withdrawn" text
);
SELECT "fleet_number_s" FROM "1912_1922" WHERE "quantity_made"='1';