calculator on actionscript 3-Collection of common programming errors

There’s a couple of ways to accomplish what you want to do, one way would be to have a method for each operation type that you plan to have your calculator support, then you can just have a switch statement that calls the appropriate method, something like this (I got lazy and just did the operation inline, if it were more complicated would probably want methods):

switch(textB.text)
{
    case '+': textAnswer.text = parseInt(textA.text)+parseInt(textC.text);
        break;
    case '-': textAnswer.text = parseInt(textA.text)-parseInt(textC.text);
        break;
    //etc.
    default: throw new Error('unhandled operator');
}

assuming that you are going to use your knowledge of the touch handlers to populate the text boxes.

While I sort of agree with arunkumar due to the lack of code provided it’s a simple enough problem with enough easy solutions to provide one. But note that on SO it is standard that you provide your current work and as much background information as is relevant.