Embed calculation logic into Button click event
<?xml version="1.0"?> <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"> <mx:Panel title="My Application" paddingTop="10" paddingBottom="10" paddingLeft="10" paddingRight="10"> <mx:HBox> <mx:Label text="Temperature in Fahrenheit:" /> <mx:TextInput id="fahrenheit" width="120" /> <mx:Button label="Convert" click="celsius.text=String((Number(fahrenheit.text)-32)/1.8);" /> <mx:Label text="Temperature in Celsius:" /> <mx:Label id="celsius" width="120" fontSize="24" /> </mx:HBox> </mx:Panel> </mx:Application>