2 sentences for 分子 (fēn​zǐ — numerator)

1. 分数线将分子和分母隔开。

   fēn​shù​xiàn jiāng fēn​zǐ hé fēn​mǔ gé​kāi.

   The fraction bar separates the numerator and the denominator.

   Source: Dong Chinese Dictionary

2. 在分数四分之三中，三是分子。

   zài fēn​shù sì fēn​zhī sān zhōng, sān shì fēn​zǐ.

   In the fraction three-quarters, three is the numerator.

   Source: Dong Chinese Dictionary