credit to https://github.com/ReactNativeSchool/react-native-calculator for example code

1. install nvm https://github.com/coreybutler/nvm-windows/releases/tag/1.1.11
2. nvm install latest
3. nvm use latest
4. npm install --global yarn
5. download calculator code from this repo
6. yarn install (within calculator code folder)
7. yarn start (within calculator code folder)
8. download expo go app on phone
9. make sure phone is on same internet connection as the computer running the app
10. scan qr code within expo go app (android) or with camera app (ios)
11. expo go automatically downloads and runs the code on phone