There is
Calculator.app located in your /Applications folder. It provides basic, scientific, and Programmer modes (command 1, 2, 3)
You can access Calculator.app in the following ways:
1.) Navigating to your /Applications folder and double clicking the app
2.) Accessing LaunchPad from the Dock, Keyboard, or Gesture. Calculator.app will be on your first screen.
3.) Using spotlight by clicking the magnifying class on the upper right hand corner or typing command-space. Then type calculator. It should be the first result.
If you used calculator.app very frequently, you can pin it to your dock after launching it. Click and hold the icon on the dock and select the appropriate option.