Don’t use a financial calculator like that one for two reasons.
Firstly, strictly it is not allowed (although the invigilator is not really likely to notice).
Secondly, and more importantly, the marks in P4 are for the workings and not for the final answer. If you just write the answer down and it is wrong (because, for example, you were using the wrong interest rate) then you will get zero for that part. If, on the other hand, it was obvious from your workings that you knew what you were doing, then you would get most of the marks even if you were using the wrong interest rate.