Dua for Exam : Allahumma la sahla

          اللَّهُمَّ لا سَهْلَ إلَّا مَا جَعَلْتَهُ سَهْلاً وَ إنْتَ تَحْعَلُ الْحزْنَ إذَا شِئْتَ سَهْلاً

"Allahumma la sahla illa ma ja'altu sahla, wa 'anta taj-alul hazna idha shi'ta sahla"

Translation :
          O, Allah! There is nothing easy except what You make easy, and You make the difficult easy if it be Your Will.


This is one of the Most benefited dua to be recited before exams with consistency.