Solution is form> body> html>
Open a text editor program on your computer. There are many options for you, but for convenience and quality, TextEdit and Notepad are two applications to use.
On Mac, click the magnifying glass in the upper right corner of the screen to open Spotlight. In Spotlight, type TextEdit and click on the program: it should be highlighted in blue.
On PC, open the Start menu in the lower left corner of the screen. Type Notepad in the search bar and click on the Notepad app that appears in the results bar located on the right side.
Paste the HTML code that creates the calculator into the document.
On Mac, click in the body of the document and press "Command+V" . Next, you need to click "Format" at the top of the screen and "Make Plain Text" after pasting.
On PC, click the document body and press "Ctrl+V".
Save the file. Click the "File" button in the upper left corner of the window and on the drop-down menu, press "Save As." - on PC, or "Save." - on Mac
Add an HTML extension to the file name. In the "Save As." menu, type the file name with the ".html" extension, then press "Save". For example, to call the file First Computer, you would save it as "MayTinhDauTien.html"
Find the file you just created. Enter the file name into Spotlight or the Start menu search bar as described in the previous step. You do not need to enter "html".
Click to open the file. The default browser will open your computer in a new web page.
Click the buttons on the computer to use. The calculation results will appear in the results bar.