CREATE TABLE table_name_31 (sales VARCHAR, peak_position VARCHAR, certification VARCHAR)

How many sales had a peak position of 1 and a certification of 6x platinum?
SELECT COUNT(sales) FROM table_name_31 WHERE peak_position = 1 AND certification = "6x platinum"
SELECT COUNT("sales") FROM "table_name_31" WHERE "6x platinum" = "certification" AND "peak_position" = 1