Plus-or-minus sign.
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+00B1 (decimal 177).
Use ± in HTML to render ± on a web page.
On Windows you can type it with Alt+177 (hold Alt and enter the number on the numeric keypad).
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