Is that how you were taught how to square a number? I was always taught you multiply the number by itself, like 210 X 210, not 210 X 1 which is what you did.
Why would I square that number? I'd do that if you gave me a side, but you already gave me the area.
Is that why you think the teacher is wrong? Did they say 210 square feet?
What you are missing is that we were NOT given the area. The wording was "210 feet square," NOT "210 square feet" NOR "210 feet squared."
X feet square means a square with a side of X feet.
The wording was "210 feet square,"
Yes, an area 210 square feet.
Wrong...you're reversing the word order. It did not say area and it did not say "square feet." The phrase was "feet square."
X feet square means a square with a side of X feet
If it said side in the question, I would agree. It didn't.
It doesn't have to say side, because that's what it means....."feet square" refers to the length of the side of a square.
Math Forum - Ask Dr. Math
And for a real world example:
Pastscape - Detailed Result: EYE PRIORY "The claustral buildings were arranged to the north, the cloister being 90 feet square." I don't think a cloister that is 9.5' by 9.5' makes any sense. Prison cells are larger than 90 square feet.