By Sanjoy Majumder
BBC News, Patna

In a congested part of Patna, capital of India's Bihar state, stands a striking yellow building - a 100-year-old mansion that has clearly seen better days.

Inside it, in a small dark room, a young bearded cleric is reading out sermons from the Muslim holy scriptures to a group of boys seated cross-legged on the floor.

They are in their late teens, some are wearing skull caps and they all listen to him with rapt attention.

At first glance, this could be any of the region's hundreds of Islamic seminaries or madrassas, where young Muslims receive religious instruction.

But this is no ordinary seminary.

After prayers, the boys head out to a classroom, pen and notebook in hand, where they listen with equal attention to a lecture on advanced mathematics.

This is the unusual setting for Rahmani 30 - a training institute which prepares talented but underprivileged young Muslims for entry into India's best engineering colleges - the Indian Institutes of Technology (IIT).

Only the top 2% make it through the stiff entrance exam.