Someone help me. I've gotten this question wrong, and I can't afford to get it wrong again. Please solve and explain?

Mr. Trundle used exactly one hundred twenty-eight ceramic tiles to cover the floor of a shower. If each tile is a square with 6-inch sides, what is the area of the shower floor?

Question

Someone help me. I've gotten this question wrong, and I can't afford to get it wrong again. Please solve and explain? 

Mr. Trundle used exactly one hundred twenty-eight ceramic tiles to cover the floor of a shower. If each tile is a square with 6-inch sides, what is the area of the shower floor?

anonymous · Answer

and it's not the first answer.

anonymous · Answer

he used 128 tiles
each tile has an area of 6*6 square inches
128*36 = ?

anonymous · Answer

your mistake was that you forgot to square the side length in calculating the area of the tile