MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH Manual page 112

This example defines two string variables ( and ), which are added
firstNum secondNum
together. The initial result is that the numbers are concatenated instead of added because they
are a String data type. The second trace statement converts both numbers to a Number data
type before performing the addition that yields the proper result. Data conversion is
important when working with data loaded using XML or FlashVars, as shown in the following
example:
var firstNum:String = "17";
var secondNum:String = "29";
trace(firstNum + secondNum); // 1729
trace(Number(firstNum) + Number(secondNum)); // 46
For more information on data conversion functions, see the entry for each conversion
Boolean function,
function in ActionScript 2.0 Language Reference: ,
Array function
, , and .
Number function Object function String function
112 Data and Data Types