keyTriggers on JavaScript Calculator

Hello,

I am currently working on setting up KeyTriggers for my calculator so I am able to use the keyboard and/or number pad when entering in the equation. I am having trouble with finding the the 4 primary mathematical operators (/, *, -, +) and the equals sign (=) keyTriggers. The symbols themselves do not qualify as a valid trigger. I have also tried putting parentheses ( ) around the symbols and they did not work. Any help would be appreciated.

Thank you,