Calculator using React, Sass, Context API

You did a good job, and is very interesting the use of the context API, i've never see it this way before, Congratulations!!

Personal feedback :

I think is it a good practice to write the code simple as possible, that includes not to separate in components all the part of the app, i mean (inputs, buttons) this way is easier to read for other devs, also would be very interesting to implement an error management ( not returning infinity when your divide by zero, the feature that allows the user to only write a operator value like [ + - / * .] once after a number, and returning the result without the decimals -- but this is just preference ).