Dua for exams ( before or during exam):
وَإِن يُرِيدُوا أَن يَخْدَعُوكَ فَإِنَّ حَسْبَكَ اللَّهُ هُوَ الَّذِي أَيَّدَكَ بِنَصْرِهِ وَبِالْمُؤْمِنِين
Wa-in yureedoo an yakhdaAAooka fa-inna hasbaka Allahu huwa allathee ayyadaka binasrihi wabialmu/mineena
“….verily Allah is All-Sufficient for you. He is the One Who has strengthened you and the believers with His help.”
[Surah: 8, Ayah: 62]
Dua after exam:
الَّذِينَ إِذَا أَصَابَتْهُمْ مُصِيبَةٌ قَالُوا إِنَّا لِلَّهِ وَإِنَّا إِلَيْهِ رَاجِعُونَ
Allatheena itha asabat-hum museebatun qaloo inna lillahi wa-inna ilayhi rajiAAoona
“who, when afflicted with calamity, say: “We belong to Allah and to Him we shall return.”” [Surah Baqarah-2, Ayah: 156]