Don's JavaScript Calculator

Your task is to create a personalized web page similar to this one. This is an html page, not a cgi page. The permissions should be 644 like other html pages, not 755. Copy the JavaScript. Fix the divide-by-zero situation. You must add at least one new (working) button. Use other creativity as you see fit. (Yeah, and delete this paragraph.)

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Validate: html5 css3