If the length of a square is 10 feet what is the area?

The area of a square is length x width, but as all sides of a square are equal, then you can simply square the length of one side of the square.
The length of the square in your problem is 10 feet, so all sides have a length of 10 feet. You can write the problem for getting the area as 10x10 or 10-squared (10^2).
The answer would be 100 feet.

21 is the answer the answer is 21