I want to sell calculator made by me and earn money.
I don't think you realise what is involved to accomplish this
do you have an electronics factory that is capable of designing and building the electronics ?
do you have a plastics factory that is capable of designing and building the cases ?
do you have a programmer(s) that is/are capable of designing the needed software ?
do you think you can build it for US$10 or less ?
do you have lots of money backing to finance your plan ?
and some one asked before and you haven't answered
what do you think your calculator can offer that the dozens of types, already out there, cannot ?
You need to be able to answer all those questions
If your answer is no to one or more of those questions, then you are going to find it very difficult to achieve
Dave