How many days can you get out 358 min?
Just divide the minutes by 60 to convert to hours. Then, divide the hours by 24 to convert to days.
Kingdom Hearts 358/2 Days is titled the way it is, most likely because of the amount of days that Roxas existed. He endured 358 days as an actual member and the 2 other days are described as '358/2' because although they are part of his existence, they take place after he leaves and 'turns' on the organization.