The plus minus sign is used to indicate the interval. From [URL /en/0033/ three] to [URL /en/0037/ seven], you can write as: 5 ± 2. On the keyboard type Alt + 0177. The number 0177 is entered on the numeric block with Num Lock on.

Also, the solidworks plus minus symbol can be used for:
[*]indicate the observational error;
[*]spread of values of any parameters.

In a [URL /en/1F5EB/ conversation] between people the plus minus symbol indicates the inaccuracy of anything.