2 sentences for 余 (yú — surplus)

1. 十五除以四，商数是三，余数也是三。

   shí​wǔ chú​yǐ sì, shāng​shù shì sān, yú shù yě shì sān.

   Fifteen divided by four gives a quotient of three and a remainder of three.

   Source: Dong Chinese Dictionary

2. 很多春联利用谐音来表达吉祥的寓意，比如“鱼”和“余”。

   hěn​duō chūn​lián lì​yòng xié​yīn lái biǎo​dá jí​xiáng de yù​yì, bǐ​rú“ yú” hé“ yú”.

   Many Spring Festival couplets use homophones to express auspicious meanings, such as 'fish' and 'surplus.'

   Source: Dong Chinese Dictionary