Adding number id possible with just property mediators

Following is a sample to demonstrate adding number id possible with just property mediators

         <property name="Value1" scope="default" type="STRING" value="5"/>
         <property name="Value2" scope="default" type="STRING" value="3"/>
         <log/>
         <property expression="number($ctx:Value1) + number($ctx:Value2)"
                   name="Total"
                   scope="default"
                   type="STRING"/>
         <log level="custom">
            <property expression="$ctx:Total" name="total"/>
         </log>