If the box is Square and it is 3 feet high then it is also 3 feet wide and 3 feet deep.

Consider the bottom of the box, an area 36 inches wide and 36 inches deep, this would be covered by 12 three inch boxes by 12 three inch boxes which is equal to 144 boxes.

Now cosider the Height of the box, 36 inches, this would hold 12 three inch boxes, therefore to fill the box you would need twelve layers of boxes, each layer containing 144 boxes, giving a total number of boxes of 144 X 12 or 1728 Boxes

Consider the bottom of the box, an area 36 inches wide and 36 inches deep, this would be covered by 12 three inch boxes by 12 three inch boxes which is equal to 144 boxes.

Now cosider the Height of the box, 36 inches, this would hold 12 three inch boxes, therefore to fill the box you would need twelve layers of boxes, each layer containing 144 boxes, giving a total number of boxes of 144 X 12 or 1728 Boxes