2 sentences

1. 二的平方等于四。

   èr de píng​fāng děng​yú sì.

   Two squared equals four.

   Source: Tatoeba

2. 在数学课上，老师正在讲解如何计算一个数字的平方。

   zài shù​xué kè shàng, lǎo​shī zhèng​zài jiǎng​jiě rú​hé jì​suàn yī gè shù​zì de píng​fāng.

   In math class, the teacher is explaining how to calculate the square of a number.

   Source: Dong Chinese Dictionary