square function

例句：

1. 1. The roomis square and has four walls.
   房间是正方形的，有四堵墙。
2. 2. Thetable is square and can fit all theplates on it.
   桌子是正方形的，可以放上所有的盘子。
3. 3. Thesquare of a number isthe product of its digits.
   一个数的平方是它的各位数字乘积。