     equals: (opts)->
       @button({
         value: '='
-        class: 'math-button operation'
+        class: 'math-button operation equal'
       }, opts)
 
     clear: (opts)->

      @button({
        value: 'fn'
        label: '&fnof;'
        class: 'math-button other'
      }, opts)

    button: (type_opts, opts)->
      ui_elements.button_builder.build(
        _.extend({}, type_opts, @opts, opts || {}))

  class_mixer(ButtonBuilder)


        do (num)=>
          @button({
            value: "#{num}"
            class: 'math-button number-specifier number'
          }, opts)

    caret: (opts)->
      @button({
        value: '^'
        label: '&circ;'
        class: 'math-button other caret'
      }, opts)

    negative: (opts)->
      @button({
        value: 'negative'
        label: '(&ndash;)'
        class: 'math-button number-specifier negative'
      }, opts)

    negative_slash_positive: (opts)->
      @button({
        value: 'negative-slash-positive'
        label: "&ndash;/+"
        class: 'math-button number-specifier'
      }, opts)

    decimal: (opts)->
      @button({
        value: '.'
        class: 'math-button number-specifier decimal'
      }, opts)

    addition: (opts)->
