On my Mac, who runs El Capitan, I can get a minus sign by invoking the special characters table: Ctrl+⌘cmd+Space. I use minus signs pretty often, so it's listed there as frequently used. Just click it or press enter if it's already highlighted, and in it goes.

If you need to enter several minus signs in a text, you can copy it to the clipboard and then paste it back freely until you need the clipboard for something else.

On my Mac, running OS X El Capitan, I can get a minus sign by invoking the special characters table: control+command+space. I use minus signs pretty often, so it's listed there as frequently used. Just click it or press enter if it's already highlighted, and in it goes.

If you need to enter several minus signs in a text, you can copy it to the clipboard and then paste it back freely until you need the clipboard for something else.

On my Mac, who runs El Capitan, I can get a minus sign by invoking the special characters table: ctrl-cmd-space. I use minus signs pretty often, so it's listed there as frequently used. Just click it or press enter if it's already highlighted, and in it goes. If you need to enter several minus signs in a text, you can copy it to the clipboard and then paste it back freely until you need the clipboard for something else.

(BTW., "who" is not a typo.)

On my Mac, who runs El Capitan, I can get a minus sign by invoking the special characters table: Ctrl+⌘cmd+Space. I use minus signs pretty often, so it's listed there as frequently used. Just click it or press enter if it's already highlighted, and in it goes. 

If you need to enter several minus signs in a text, you can copy it to the clipboard and then paste it back freely until you need the clipboard for something else.