Daniel discovered that the number of customers buying from his shop doubles every week . As a sales promoter ,he intends to give a free soda to whoever buys from his shop during the 6th,8th,12th week . he wants to purchase the sodas early enough but he doesn't know how many of them he should buy for the promotion . there were only 4 customers in the first week . Task : help Daniel to find how many sodas he needs to purchase for the promotion.​