Question: How many games were sold on PS3 platform in Japan?
SQL: SELECT SUM(T1.num_sales * 100000) FROM region_sales AS T1 INNER JOIN region AS T2 ON T1.region_id = T2.id INNER JOIN game_platform AS T3 ON T1.game_platform_id = T3.id INNER JOIN platform AS T4 ON T3.platform_id = T4.id WHERE T2.region_name = 'Japan' AND T4.platform_name = 'PS3'