CREATE TABLE table_4105 ("Player" TEXT, "County" TEXT, "Matches" FLOAT, "Innings" FLOAT, "Runs" FLOAT, "Average" TEXT, "Highest Score" TEXT, "100s" FLOAT, "50s" FLOAT)

How many 100 for the player with 3 50s?
SELECT "100s" FROM table_4105 WHERE "50s" = '3'
SELECT "100s" FROM "table_4105" WHERE "50s" = '3'