yikes, that’s unfortunate. there’s nothing wrong with datatyping–as long as you pick the correct type (which would be movieclip, not number, in this case).
gotta go with adobe on this one:
Because data type mismatches trigger compiler errors, strict data typing helps you find bugs in your code at compile time and prevents you from assigning the wrong type of data to an existing variable. During authoring, strict data typing activates code hinting in the ActionScript editor (but you should still use instance name suffixes for visual elements).
Using strict data typing helps ensure that you don’t inadvertently assign an incorrect type of value to a variable. Flash checks for typing mismatch errors at compile time, and displays an error message if you use the wrong type of value. Therefore, using strict typing also helps to ensure that you do not attempt to access properties or methods that are not part of an object’s type. Strict data typing means the ActionScript editor automatically shows code hints for objects.