d the dimensions of a box with an open top that has vertical sides, a square bottom, a volume of 256 cubic meters and the least possible surface area?...

How do you find the dimensions of a box with an open top that has vertical sides, a square bottom, a volume of 256 cubic meters and the least possible surface area?

PS: I am struggling to answer the question so I need help to understand how the work is done, this is what paid tutoring services are for otherwise help me revise the question! Please don't cite academic dishonesty when i have asked such questions before that have been answered!