What is the number of total candidates when registered voters is 47742?
CREATE TABLE "congress" (
  "electoral_district" text,
  "registered_voters" real,
  "seats_in_congress" real,
  "candidates_per_party" real,
  "participating_parties" real,
  "total_candidates" real
);
SELECT "total_candidates" FROM "congress" WHERE "registered_voters"=47742;