You won't be able to use any kind of calculator in these examinations.

You need to devote sometime on improving your calculations.Try to remember squares of first 30 no's. and other multiplication tricks to kick start your calculation speed.

No, calculator is not allowed in any entrance test of Engineering whether it is national level entrance like Jee, state level exam like IPUCET and private exams like BITSAT, VIT,SRM etc. You can also check the exam guidelines as most of them mention that "No Electronic Gadgets are allowed in Exam Hall including Calculator".

Good Luck!!!