How long is 400 feet square feet?

Answer 1

Answer:

400x4 = 1600 feet

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The above is pure nonsense. Where on earth did the 4 come from?

In any case the question has no meaningful answer. A foot is a measure of length or distance while a square foot is a measure of area. The two measure different things and, according to basic principles of dimensional analysis, conversion from one to the other is not valid.