The Squared Dot Operator symbol (⊡). Copy and paste it, or use its Unicode, HTML, and CSS codes.
More from Math.
The quickest way is to copy ⊡ from this page and paste it anywhere. You can also insert it with its Unicode, HTML, or alt code listed above.
⊡ is U+22A1 (decimal 8865).
Use ⊡ in HTML to render ⊡ on a web page.
On Windows you can type it with Alt+8865 (hold Alt and enter the number on the numeric keypad).
Yes — copying is completely free and unlimited, and works right in your browser with no sign-up.