implement financial microservice using node.js | python | R
@wizard I would share here something .
If you have complex calculation or any type of calculation do it in db end if feasible. 
The best approach
postgres
to do this type of process is to make function (PL\SQL) block . If you are using postgres create all calculation in postgres .
This is why node.js was design , no calculation in node.js end . 
mongodb
if you are working with mongodb with this approach then i will recommend you to go with
Stored JavaScript in MongoDB
I'm developing a tourist web app with node.js and microservics.
I need to develop a pricing service which will do all the calculation for the guest (price for night, taxes, VAT, discounts etc).
Moreover, I need those calculation will be easy to dynamically change and control.
From my past experience, doing those calcs in common web programming languages and/or storing math formulas in the db end with a mess.
Are there any alternative solutions for this? From what I read so far language like python, R or Java can fit to the job. However, is there any specific library within those which aimed for pricing?