Deepak,
There are some centers that do NOT provide a calculator. (I know... I know... they should all follow the same operating procedures... but they don't...)
If you are in a center that does not provide a physical (handheld) calculator to you, then you will have the option of launching the Windows calculator on the exam computer screen. If you want to be 100% certain, then the best thing to do is to call your testing center (or stop by) and ask.