A neat little thing you can do in most operating systems is to enter a mathematical equation in the system’s search field and get the result back.
This also works on GNOME Shell but if it’s not working for you, go to Settings → Search and make sure that the App Search toggle switch is on at the top and that the Calculator app’s toggle switch is on under Search Results.
(For some reason, the latter was off for me on Fedora Silverblue.)
