plus minus keys problem

Unity Engine
1

I am adding music to my game that can be adjusted in volume by user input. This script works:

if (Input.GetKeyDown("2")) { 
	if (audio.volume < 1) {
		
	audio.volume += .05; 
	}
} 
if (Input.GetKeyDown("1")) { 
		if (audio.volume > .1) {
	audio.volume -= .05;
		} 
}

But when I tried to use “+” in place of “2” and “-” in place of “1”, the “+” did not work and the minus number pad did not work either.
Any ideas why this is happening?
Thanks.

2

First of all, note that numpad keys and regular keys are different: numpad keys are represented as [-] [+]
Also, you would have to use = for the other plus sign, since = is the main key (I’m not sure if Unity will detect + if you hold shift and press it)

if (Input.GetKeyDown("=") || Input.GetKeyDown("[+]")) { 
   if (audio.volume < 1) { 
       
   audio.volume += .05; 
   } 
} 
if (Input.GetKeyDown("-") || Input.GetKeyDown("[-]")) { 
      if (audio.volume > .1) { 
   audio.volume -= .05; 
      } 
}
3

Thanks for your help!
BTW, “+” is “;” and “-” is the default with “=” being the secondary choice for that key on my keyboard. That should be standard with Mac and Windows, right?