square (as in square foot, square mile, square root)

Two squared equals four.

My teacher taught me that you can take the square root of a negative number.

What is two to the power of four multiplied by three plus four squared plus three?

The mainland of China covers 96,000,000 square kilometers, and it is the largest country in Asia, as well as the third largest in the world.

I still remember the first time I was in China; I was in Shandong, and I realised that that province alone is twenty six thousand square kilometres bigger than England.