How do I reinstall my calculator on my iPhone 13 pro?

Are you talking about the calculator app that came with the iPhone, or another one you had downloaded on your previous iPhone?

Redownload apps and games from Apple - Apple Support

You should be able to access the calculator from Control Center

Access Control Center on your iPhone and iPod touch - Apple Support

If it's not shown, you can to into Settings > Control Center and add the calculator

If it's missing from your Home Screen, you may have removed it, in which case it'd reside in the App Library.

For that scenario:

From your Home Screen, swipe left until you get to the App Library.

Swipe downward and you'll get an alphabetical list of your apps.

Locate the app in the list or type the app name into the search field

Once you've located the app, tap/hold then drag it and it'll pop out to your Home Screen.. place it where you like

Organize the Home Screen and App Library on your iPhone - Apple Support

Kathyhampwhite Said:

"How do I reinstall the calculator on my iPhone 13 Pro?"

-------

What to Perform:

A. Start with a Restart:

Restart your iPhone, and see if it then is fixed.

Also...

B. Reset the Home Screen Layout...

Go Here: Move and organize apps on iPhone - Apple Support

Scroll to: Reset the Home Screen and Apps to their Original Layout

1. Go to: Settings
2. Tap: General
3. Tap: Reset
4. Tap: Reset Home Screen Layout