Talk:Significant figures

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One of the 500 most frequently viewed mathematics articles.

Reminder on thousands and decimal separators[edit]

Note to editors from non-English-speaking countries: please be aware that this article follows the usage of most English-speaking countries in using a dot (.) to indicate decimals, and a comma (,) to separate thousands. Quite a few non-English-speaking countries do it the other way around, which has caused confusion on this and other articles. See Decimal separator for more information. (I wonder if it's worth creating a template for article space?) --Calair 12:28, 1 June 2007 (UTC)

Also see Wikipedia:MOSNUM § Delimiting (grouping of digits). —[AlanM1(talk)]— 20:51, 21 July 2013 (UTC)

Thousands separator[edit]

I have now (for the second time) fixed someone's change from , to . in a number where the comma is used as a thousands separator. I have now also removed all the commas which are used as thousands separators and replaced them with spaces (I guess non-breaking spaces would be even better) because we have the least chance for misunderstanding if we use a point as a decimal and no commas at all. --Slashme 05:20, 8 November 2007 (UTC)

Clarify a confusing point[edit]

The article uses the terms "significant figures" and "significant digits" interchangeably. Is there a mathematical reasoning to the usage of one word in some places and the other in other places, or is it simply a matter of preference? If it is a matter of preference then i suggest all instances of the term "significant digits" be replaced with "significant figures" in order to make the article clearer and because the article is about significant figures not significant digits. —Preceding unsigned comment added by 71.236.29.119 (talk) 03:47, 10 December 2010 (UTC)

I think that's just American vs. Commonwealth English. -- Beland (talk) 04:35, 3 March 2013 (UTC)

Arithmetic Example[edit]

I think the arithmetic section could use two quick examples, one for each rule.

For example, 1300 x 0.5 = 700. There are two significant figures (1 and 3) in the number 1300, and there is one significant figure (5) in the number 0.5. Therefore, the product will have only one significant figure. When 650 is rounded to one significant figure the result is 700.

For example, 1300 + 0.5 = 1301. There are zero decimal places in the number 1300, and there are is one decimal place in the number 0.5. Therefore, the sum will have zero decimal places. When 1300.5 is rounded to the ones decimal place (zero decimal places) the result is 1301. —Preceding unsigned comment added by 99.32.166.179 (talk) 01:30, 9 January 2011 (UTC)

This is covered under Significance arithmetic, and I think the second example is wrong. It should be 1300 + 0.5 = 1300, since addition uses the position of most significance in the least significant number, which would be the hundreds place of 1300. -- Beland (talk) 04:43, 3 March 2013 (UTC)

I think the example for logarithms in the Arithmetic section is wrong: 3.000 has 4 significant figures, and if the number of digits in the mantissa should be equal to the number of significant figures, then log(3.000×10^4)= 4.4771 (4 decimals), rather than 4.48 (2 decimals). I'm not 100% sure about this, so I would like to hear someone else's opinion before correcting... Oghin (talk) 21:35, 18 March 2013 (UTC)

I checked some additional sources, which confirm this, so I decided to go ahead and correct the example. Oghin (talk) 00:25, 19 March 2013 (UTC)

History of sig figs[edit]

The history of significant figures - who came up with it? When were they first used? When did they come into general use and start being widely taught? - would make a nice addition to the article. I couldn't find anything on this topic when I looked today, but someone must know. 99.65.213.158 (talk) 03:47, 19 March 2011 (UTC)

It appears to have been in the 1970s and 1980s, right when the government was starting to push for the removal of chemistry from chemistry, due to the protest movements. It was likely implemented as a filler in chemistry so that a full semester or year could be taught in bullshit. Sig figs serve absolutely no purpose and are just a distraction.--Metallurgist (talk) 00:24, 12 September 2012 (UTC)
Uh, no. Google ngrams and Google Books search 1800–1854. —[AlanM1(talk)]— 20:44, 21 July 2013 (UTC)

Too-easy misinterpretation: 'trailing zeroes'[edit]

The early introductory material says: ...

The significant figures (also called significant digits) of a number are those digits that carry meaning contributing to its precision. This includes all digits except:
leading and trailing zeros which are merely placeholders to indicate the scale of the number.

I've wracked my brain to realize, finally, that the context here is that the number 32,000,000 might have precisely two significant digits. But, the number 0.032000 probably has five. Thus, I think the introductory material should be clearer and is, as it stands, quite misleading. I'd fix it myself, but fear incurring the wrath of Those Who Care. — Preceding unsigned comment added by Rkolstad (talkcontribs) 17:17, 6 September 2012 (UTC)

Thanks for that comment; I've tried to clarify the intro. -- Beland (talk) 04:45, 3 March 2013 (UTC)
I went a little further, separating out leading zeroes are always insignificant (as stated correctly further down). —[AlanM1(talk)]— 20:35, 21 July 2013 (UTC)

Merged from Arithmetic precision[edit]

I implemented the requested merge from Arithmetic precision; I left the comments at Talk:Arithmetic precision in place. -- Beland (talk) 03:41, 3 March 2013 (UTC)

Requested by whom? I do not see a discussion. Did at least two users express their support for this dubious deal? Incnis Mrsi (talk) 18:29, 20 March 2014 (UTC)

Problems[edit]

This article seems to have been eroded by a number of edits that sound like WP:OR at best, structure that's gotten kind of scattered, etc. One editor added a "cite" (Serway) that I fixed, but the referenced 1990 edition is way out of print and I couldn't even find an ISBN for it. I added some maintenance tags and cleaned up what I could, but it could really use a re-work against a good modern source or two if someone happens to be studying such a text and would like to do so. —[AlanM1(talk)]— 20:33, 21 July 2013 (UTC)

Mixed Tables of Sig Fig[edit]

Mathematics software goes further. ex. in Mathematica one can specify a number with: [base^^][Real.m]([``]|[`])[*^n] where `` is acc, ` is prec, n means *10^n, and Real is not in rational form. Calcualtions take sig, acc and prec into account. Infact all non-rational numbers do, though new users are typically un-aware because they are displayed plainly. Competing software like Matlab have alternate ways of achieving the same.

How to sqeeze such numbers in a table is another topic because what to show (so the reader is not lied to) uses all the rules for sig fig, acc, prec mentioned above. Usually: the job is never done, excepting in formal science publications like CRC's handbook of chem & phy, and one should be aware it hasn't been.

fNBookForm2 displays scientific numbers in Mathematica tables in texbook style and does all mention rules (sig, acc, prec) and width, and has 4 rounding modes (off, normal: ignore fractional sig, round in fs, round off fs). It reads shorthand. It can display power letters as well. — Preceding unsigned comment added by Sven nestle2 (talkcontribs) 21:56, 6 October 2013 (UTC)

Confusion about "Estimating Tenths"[edit]

If I have a ruler marked with millimetres as the smallest division then how can I report a measurement as 2.54 cm. I can say it is 2.5 cm or 2.6 cm. But how can someone know that whether it is 2.54 or 2.55 or 2.52. If this scale has a least count of 1 mm then how can it shows measurements with 0.1 mm accuracy. Naveeagrawal (talk) 05:42, 24 January 2014 (UTC)

Zeros in the Middle[edit]

I've found 3 articles on the web explaining the meaning of significant digits. All give many examples but none give an example with zeros in the middle. They do not address the fact that 20.002 has five significant digits. All the talk of leading zeros after the decimal and trailing zeros confuses this issue. foobar (talk) 01:16, 8 February 2014 (UTC)