The study of magic squares has a long, long history. In ancient Babylonian times, these array of numbers were held to have magical powers. Over the years, they have also served as protective ...

On the diagram you see a simple example of a magic square, one celebrated as being drawn by Albert Dürer in his picture of “Melancholy,” painted about the year 1500 (Fig. 1).

Twitter is introducing new rounded square profile pictures for brands and businesses. It’s also rolling out a new badge to show one account’s connection to another.