Yes, it's right, iPad does not have a native calculator. And navigating through the App Store looking for a good one and completely free (Ads and in app purchase) you will figure out that there is none. And that's why I'm creating a new one, trying to stay as close as possible to the iPhone calculator design and functionalities.
Inside iOS-Calculator cloned repository type pod install, it will install some dependencies.
Open Calculator.xcworkspace file with Xcode and press ⌘ + R
