Plus-minus sign

How to type it

Mac: Shift + Option + =. Windows: Alt + 0177 on the number pad.

Common uses

• The plus-minus sign states a margin of error or tolerance, as in 5 ± 0.2 cm.
• Polls use it for the margin of error, such as 52% ± 3 points.

Less common uses

• The quadratic formula uses ± to give both roots of the equation at once, one with plus and one with minus.
• Scientists attach ± to measurements to report uncertainty, so 9.8 ± 0.1 means the true value likely lies between 9.7 and 9.9.