h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Significant Figures - A5793339
Author: melee_bowser - U2007328

I've fixed it up and should be good enough to be in the edited guide.

This first quotation doesn't make English sense, is there a a word or two that is incorrect?

"in a measurement consists of all the digits known with certainty plus one final digit, which is somewhat uncertain or estimated." -Mordern Chemistry

Typo:

Example- 60.3 g has three sifnificant figures.> significant

Might I be the volunteer idiot here

I have no idea what this entry is about. Well, that's not quite true: it's obviously about something mathematical. But beyond that, you haven't really explained what is so significant about 'Significant Figures', what they're for, how they're used in maths and so on.

There may well be the core of something for the Edited Guide here, but, as it stands, it seems a bit 'bare bones'.

I'll have to agree with Trin, I haven't the foggiest what's going on in this entry.

Therefore, we can all sit around here and jig everything around.

First of all however, welcome to Peer Review!! It's good to see a new person striking out so soon after joining, well done If you have an questions about what you're supposed to do with this entry and the Peer Review process then don't hesitate to ask.

Now, back to the entry...

Your first quotation needs to include "significant numbers", you can't just lead on from the title of the entry. You've also spelt Modern wrong

I think you then need to give a quick explanation that is read-friendly about what a significant number is, an example of one, what they are used for etc etc. Having read the whole entry I do know what a significant number is but I think they need more introduction and an explanation of why anyone wants to care about each number being significant.

You also need to jig your wording around. I can tell that you've copied a lot of this straight from your chemistry book, which is a definite no-no. Think about how you would explain all of this to a complete dunce, then write it down. That's the way to take mathematical entries me thinks

Kat

You've included the rules for determining significant figures, but you haven't told us what they are. You need to start this with a discussion of measurement, tolerances and accuracy. Telling someone that 7 has 1 significant figure and that 7.00 has three doesn't tell them anything, as it doesn't mean anything to them.

Thank you everyone for your comments. I'll be updating the entry soon.

it's updated. Anything else?

It's certainly better. But I'll leave it to the non-mathematicians to say whether they can understand it or not. I can understand it because I already know about significant figures.

One small point. You say nonzero numbers. What you mean is numbers that have no zeroes in them. But nonzero just means they are not equal to zero.

It is zeroes, not zeros.

Anything else I need to fix?

O.K. I've fixed the entry up a bit with the GuideML. Does it look better?

You've rounded 8.95 to 8.9, when it should be 9.0.

Thanks, is there anything else?

Your footnote, "In this entry, nonzero will refer to numbers that do not have zeroes in them" seems unnecessarily arbitrary. Nonzero has a standard meaning, "greater or less than zero", hasn't it? Do you need to invent a confusing exceptional usage? Wouldn't it do better to head the section "Determining the Number of Significant Figures for Numbers Without Zeroes" which needs no footnote.

I also find other parts confusing; I'll get back to them later.

I thought significant figures had something to do with rounding horrific looking numbers for the sake of simplicity:

eg 234,567,890 is 235,000,000 to 3sf (the zeros are insignificant as in standard form they are made to disappear - 2.34 x 10^8 to 3sf)

Alex

Yes; that is the primary usage I had heard of. Should you mention the two uses -- (a) how many sig figs a number has and (b) how many you wamt to make it have?

Significant figures, first, are not to do with accuracy but precision. You cannot give an answer more precise than your data, so you cannot have more significant figures in your answer than in the numbers you put in.
You really do need to change "non-zero numbers" to "numbers containing no zeroes", because that's standard usage.
As an aside - in Edexcel A-Level maths exams, all answers must be to three significant figures unless otherwise specified.

That's the same on American AP exams - at least, I know for a fact that it's the case on the AP Chemistry exam; I'm not sure about other math and science courses.

what you did is scientific notation. For some odd reason, you rounded the number to have a lot of zeros. You didn't multiply or divide the number by anything, so the rounding was, in fact, worthless.

my earlier reply is for Alex.

Alex is completely right. It wasn't an odd reason, it was the reason he gave, for simplicity.

The topic of significant figures is an important one, but I don't feel it is explained adequately by this entry. The entry gives the details of how to calculate how many significant figures in the result of a calculation, but it doesn't explain adequately what significant figures are all about, the difference between accuracy and precision, and how if I have a couple of pounds in my pocket, I don't have exactly 2 euros and 91 cents.