The analogy at the end (section IV) made the whole article easier to "get".
...an answer cannot be more precise than its data. Or its question. ...an answer cannot be more precise than its data. Or its question.If you're measuring values under uncertainty, then his explanation makes some sense. But that's a property of measurement and uncertainty, not of numbers or arithmetic.
For a scientist, or someone working with real world data, this should never be the default assumption.
Besides, in the paragraph with the arithmetic he explicitly talks about significant figures. In context, the answer is unambiguously 7 .