JS Math Testing

var textbox1 =  document.getElementById('textbox1');

var select1 =  document.getElementById('select1');

try
{
var math = {
  square: function(x){
     return x * x;
  },
  cube: function(x) {
    return x * this.square(x);
  }
};
var num = 4;

textbox1.value = 'num: ' + num;
textbox1.value += ' , square: ' + math.square(num);
textbox1.value += ' , cube: ' + math.cube(num);
textbox1.style.width = '300px';

}catch(e){
   textbox1.value = e.Message;
}