As you can see in the image, this is a Calculator. You will find a calculator program the same as this on a very familiar website like CodePen, but that program will be very difficult. If you are a beginner or watching for simple code then definitely difficult you to understand.
In the image, there are some buttons and numbers. When you click on that specific button, the number of that button will be shown on the display.
See the Pen
How to make Working Disgital Calculator using HTML CSS & jQuery by CH RAHMAN (@Sufya)