I pray this finds you in the best of health and faith, insha'Allah. (1) The minimum number of verses which need to be recited in the voluntary prayers is three, just like the obligatory prayer, or one long verse which is the extent of three short verses.
Answer Praise be to Allah. The Standing Committee for Issuing Fatwas was asked the following question: What is the number of men required for Jumu`ah prayer to be valid? Some people say that it is not valid with less than forty men, and if there is one less than that, they should pray Zuhr. They replied:What is the minimum number of ayat are you allowed to recite in Salah after Al-Fatihah? As you guys already know, there are chapters in the Quran that are so long, that I don't think any of us could recite it all in one standing. Furthermore, there are single verses in the Quran that are so long, it could be as if they're their own Surahs.
For example, Surat al-Ikhlas, al-Kawthar, or al-'Asr are sufficient in any unit of any prayer after the Fatiha. Three verses are the wajib amount, and any three verses can do this - even short ones like the first three of Surat al-Rahman.
WP7ep5C.