Iphone 7. Calculator icon shows in Control Centre. How create its icon on Home Screen?

If you're sure that the Calculator icon is not in a different screen page or "hidden" into a folder, open App Store and search for Apple Calculator, then redownload it.

Regards

Giulio

You may use third party Calculator apps from App Store.

Tap on the calculator icon until it's shaking and draw it onto the home screen. After that tap on the home button. Shaking stops.

ervau