How many marks should i have in bits entrance test to have a set in bits college where as i got 920 marks in 10+2

Your branch of choice is important when thinking about a seat in BITS. The campus also matters. For example - Cutoff for Computer Science is different from the cutoff of Mechanical engineering. Cutoff of Computer Science in BITS Pilani and Goa campus are different. The marks are calculated out of a total of 450. That being said, the general pattern of cutoffs is:
Course                       Pilani           Goa          Hyderabad
Computer science.   378              347            334
Mechanical                313              283            274
ECE                              338              308            298
Chemical                    280              260            247

Good luck