Provide the number of games sold in North America on the PS4 platform.
number of games sold refers to sum(multiply(num_sales, 100000)); in North America refers to region_name = 'North America'; on the PS4 platform refers to platform_name = 'PS4'
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 = 'North America' AND T4.platform_name = 'PS4'