Here are the Saraswati mantras for increasing concentration in studies:
For Knowledge:
Vad Vad Vaagwaadinee Swaha
For increasing Intelligence:
Om Aing Hreeng Shreeng Vaagdevyai Saraswatyai Namah ||
For Exam:
Om Aim Hrim
Kleem Maha Saraswati Devaya
Namaha
For Excellence:
Saraswathi Namasthubhyam,
Varadey Kaamarupinee
Vidhyarambham Karishyami,
Sidhir bhavathu mey sada
For Knowledge:
Vad Vad Vaagwaadinee Swaha
For increasing Intelligence:
Om Aing Hreeng Shreeng Vaagdevyai Saraswatyai Namah ||
For Exam:
Om Aim Hrim
Kleem Maha Saraswati Devaya
Namaha
For Excellence:
Saraswathi Namasthubhyam,
Varadey Kaamarupinee
Vidhyarambham Karishyami,
Sidhir bhavathu mey sada