It's a simple calculator with few operators, please take a look and give me feedback on what I can do to shorten it (and run the same way it does with this coding) or ways to improve it (extra coding to make it efficient?)
@Komil So, let's say you've bought the domain komil.work. You now own the domain name, but you still have to tell your domain where to get content from. (Until you do this, it'll show a basic page showing that the website has been bought, but this page is otherwise useless.) This can be done by pointing a DNS record to a web server. Web hosting companies, such as HostGator or Hostinger, will store the files and data for your website on their servers and handle all the delivery for you. However, you have to pay in order to actually use their servers, kind of like renting an apartment. Github isn't a web hosting company, and therefore they make their money in other ways. This allows them to offer basic, free web hosting for their users. Github won't be as feature-rich as proper hosting companies, but for a basic, personal website, it'll do. Once you own your domain and have successfully set up your Github Pages site, you can use a DNS record to point your domain name towards the Github server where your website is hosted, and the data will be fetched and sent to whoever is trying to see your website.
To simplify, think of your domain name as your house address. You own the property, but until you have a house built, visitors will only find an empty lot.
To get started with Github Pages, go to this link and follow the interactive guide. Select "User or organization site" for the first option it gives you, and "I don't know" for the second. This will show you how to install the Github Desktop client as well as how to create a personal site, rather than a project one.
Alternatively, you could also host your website on Repl.it, but I wouldn't recommend that. Github is far more reliable.