You could arrange them that way, but the goal is to find the way to pack the small squares in a way that results in the smallest possible outer square. In the solution shown, the length of one side of the outer square is just a bit smaller than 12. If you pack them normally, the length would be larger than 12. (1 = the length of one side of the smaller squares.)
Why can’t it be stacked up normally? I don’t understand.
You could arrange them that way, but the goal is to find the way to pack the small squares in a way that results in the smallest possible outer square. In the solution shown, the length of one side of the outer square is just a bit smaller than 12. If you pack them normally, the length would be larger than 12. (1 = the length of one side of the smaller squares.)