We have a significant number of significant questions (see also significant figure 1) that are asked here solely because they're problems people face in chemistry classes. Examples are:

Significant figures used to imply stated error?

When expressing a quantity, do the non-significant figures determine whether you round up the last significant figure? - Actually, this question sparked this meta post.

There are two opposing views:

  • These questions should be off-topic here, since they're really math. No chemistry knowledge is required to answer them.
  • These questions should not be off-topic here, since even though they're not about chemistry, the expertise of a chemist is useful in answering them.

TBH, I'm for one, since some chemists are also good chefs and that doesn't mean people can ask about cooking here. So, theoretically, what should we do about them? Close? Migrate to math.SE$\,$1? Leave alone?

Additionally, I think we should have a custom close reason or what if you guys agree with closing them.

Note that this search term returns quite a number of results.

Significant otters.
Significant figure 1: Significant otters

  • 1
    $\begingroup$ Now I'm expecting someone to say "Do they hurt?" but please note that we could've left homework dumps open because "does helping someone hurt?". Just making sure I won't hit the wall of that analogy. $\endgroup$
    – M.A.R.
    Commented Oct 4, 2015 at 19:49
  • 1
    $\begingroup$ It hurts me that I can't ask if they hurt Y,...,Y $\endgroup$
    – Jan
    Commented Oct 4, 2015 at 20:20
  • $\begingroup$ I wouldn't migrate to math.se. Just going on my gut, it doesn't seem like the right match. Maybe to stats.se. However, IMO, for general science questions, such as questions about sig figs., there seems to be enough justification to have them on whatever science stack they are asked. $\endgroup$
    – Hal
    Commented Oct 4, 2015 at 20:36
  • $\begingroup$ Just browsing and came across this - but for what it's worth, we generally consider questions about metrology (including significant figures and uncertainty) to be on topic on Physics. $\endgroup$
    – David Z
    Commented Oct 14, 2015 at 17:27

2 Answers 2


The ideas of uncertainty as a quantifiable attribute and statistical significance of results are among the most important concepts of all fields of science and technology. Hence, we may find related questions on several sites. Depending on the particular problem, some questions may even find better answers on other sites than on Chemistry Stack Exchange. However, the fact that a question is on topic on another site does not make it off topic on Chemistry. (Also note that, in most cases, other sites don’t migrate questions to Chemistry even if they could find better answers here.)

The basic principles of the manifold rules and guidelines concerning uncertainty found in all fields of science and technology today are actually quite similar. Arguably the best references for these basic principles are the famous Guide to the expression of uncertainty in measurement (GUM) and the International vocabulary of metrology (VIM). These guides are published by BIPM, IEC, IFCC, ILAC, ISO, IUPAC, IUPAP, and OIML, which illustrates the international consensus on this topic.

The concept of significant digits is just a simplified form of the concept of uncertainty; however, it is ubiquitous in chemistry. A number is considered to lie within the error limits of the last significant digit(s). When a number is given without any further information, it is generally interpreted so that the last digit is rounded with a rounding range equal to 1 in the last digit. It essential that everyone understands this concept, and it is no surprise that we receive questions relating to this topic.

Of course, working with the concept of significant digits is only mathematics. However, all quantity calculus is merely performing mathematical operations on quantities. Following this reasoning, we could migrate all questions relating to physical chemistry or similar fields to Mathematics Stack Exchange since all of these questions are actually mathematics. The reason for this is that mathematics is the language in which we write such questions and answers. We might just as well migrate all questions to English Language & Usage Stack Exchange since the texts of all questions are written in English.

  • 1
    $\begingroup$ +1 for migrating all phys-chem questions to maths.SE =D $\endgroup$
    – Jan
    Commented Oct 7, 2015 at 8:18
  • $\begingroup$ So you're saying we should keep them? ლ(ಠ益ಠლ) On the serious side, we seriously need to introduce a tag for them, or we'll be seriously in serious trouble, seriously. $\endgroup$
    – M.A.R.
    Commented Oct 8, 2015 at 19:14
  • $\begingroup$ I hope I understood correctly, hnece: I agree keeping those questions as on topic. $\endgroup$ Commented Oct 14, 2015 at 12:27
  • $\begingroup$ @M.A.R. About one and a half year later: chemistry.stackexchange.com/questions/tagged/… $\endgroup$ Commented Mar 27, 2017 at 4:18

So, theoretically, what should we do about them?

From my point of view Math.SE is the only appropriate place for such questions (it already has about 60 of them as OP mentioned) but I admit such opinion might seems quite radical. Hey! Physics.SE currently has 26 questions on significant figures as well, so why should not we allow such questions here on Chemistry.SE?

But, as I said, I think questions about significant figures should be on-topic on Math.SE only, since they're purely mathematical: at the end of the day, it is a simple arithmetic. If a person that asks about significant figures do not admit that, chances are very high that it is just another "do my homework for me" question which will be anyway closed here (as well as on Physics.SE), but not on Math.SE.

  • $\begingroup$ Agreed. We don't have good tags for them, and we're not banning them or something, just migrating to math.SE. $\endgroup$
    – M.A.R.
    Commented Oct 6, 2015 at 10:01
  • $\begingroup$ @inɒzɘmɒЯ.A.M Migrating is a case-by-case business at the moment, one that still means, that the question needs to be decidedly off-topic here. $\endgroup$ Commented Oct 14, 2015 at 12:25

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