At first there was a psychometric test consisting of psychological questions, very interesting. I think around 120 people were called for the hiring process. There were 7 rounds (including psychometric test). The 1st round was an extempore round where everybody was given abstract words: shoes, trees,mangoes,tyres,7,milk, hilsa, Brahmaputra etc. From this round around 60 people qualified. The 2nd round was a group case study round. Groups were given case studies to solve. From this round 30 people were shortlisted for the 3rd round. In this round everybody had to solve a puzzle (maths based). 15 people qualified this round.
The 15 people were asked to come the next day for the PI (technical+ HR). The candidates were highly screened. They were asked questions from GK, Geography, History, Physics, Maths, current affairs, statistics, econometrics, economics etc. 45 min for each candidate. Out of the 15, 5 people were selected for the HR round where they were given 3 cumbersome sums on statistics. From them, 3 people were given the job.
In short, it was a very difficult process