Originally Posted by HowlerKarma

3.1416 and 3.14160 are exactly the same number.


Well, perhaps they are-- and perhaps they are not. It's ambiguous without additional information.

No. There is no ambiguity. There is no additional information to be had.

Look the whole notion of significant figures is just a muddleheaded oversimplification of something that should be done properly with random variables (and you're back to mathematics again). And that's too advanced a topic for an elementary school class on basic arithmetic in the decimal system.