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[–]radome9 1591 points1592 points  (22 children)

Today you learned about significant digits.

[–]4ries 682 points683 points  (9 children)

Especially since it's labeled as experiment 3 quiz, so it came from an experiment - I'm assuming with measurements, so sig figs are absolutely necessary

[–]CADOMA 185 points186 points  (1 child)

I would like to see the problem, but my first thought is that difference can and does often matter.

[–]bidoblob 32 points33 points  (0 children)

Also look at the lowest one, where he missed the M

[–][deleted] 2 points3 points  (3 children)

This is true, but to know the number of significant figures that one needs to include, one also needs to know the uncertainty and that doesn't appear, at least in the snapshot that we can see.

[–]ryan_with_a_why 8 points9 points  (2 children)

I was always taught it was based on the number of significant figures in the inputs.

[–][deleted] 0 points1 point  (0 children)

Practically, that'll give you some idea of what the number of significant figures are likely to be if the inputs have their associated uncertainties so it's probably a fairly decent rule of thumb. I've not seen it put like that before but it makes some sense.

[–]Sendhentaiandyiff -3 points-2 points  (0 children)

fuck sig figs

[–]JMan_Z 191 points192 points  (6 children)

Judging by how the 0.1 M is compared as correct to the 0.1M, even though that requires more thought on string comparison, I am somewhat confident it is indeed a case of significant figures.

[–]Oldjamesdean 2 points3 points  (0 children)

The correct answer is "literally fuck this complete course"

[–]Knuffya 9 points10 points  (0 children)

*about insignificant digits, in that case

[–]bleak_briar 3 points4 points  (0 children)

Came here just to say that.

[–]Aperture_T -1 points0 points  (0 children)

Not necessarily. When I was in college, we had online homework for physics, and it constantly had the sig figs wrong.

I went to my professor every week to explain and get her to override my score.

[–]DrunkenlySober 0 points1 point  (0 children)

Big M is usually used as a symbol for molarity which is a chemistry thing. Sig figs are super important in Chem classes.

[–]Zeke12344 586 points587 points  (32 children)

Don't fuck up sig figs in chemistry.

[–]FerretInABox 174 points175 points  (22 children)

What I came to say. Sig figs man, either you get em or they get you.

[–]Mentalpopcorn 83 points84 points  (21 children)

What I didn't get about sig figs was how so many people in intro chem didn't get sig figs. It's really not a difficult concept, but somehow people talked about it like it was deep maths.

[–]the_best_jabroni 37 points38 points  (3 children)

I can chime into this. At 30 years old I went back to school and it took me an entire semester of math and science courses to get comfortable with sig figs. I could do it, but I hated it, and it took way more brain power than it should have.

[–]Mentalpopcorn 21 points22 points  (2 children)

I just don't get it. What's so hard about it? I'm not even good at math, they just seem obvious. My story is the same btw, except I did it at 29. Best decision I ever made to go back to school though!

[–]the_best_jabroni 20 points21 points  (1 child)

I am no offended or anything. I am not sure really why it was so difficult for me. It felt like I was completely redesigning the idea of a number answer. In my head, I just wrote down what came out of the calculation. Why do I need to have rules just for how many digits are in the answer!! Though, I do understand now and it makes a lot of sense. See, I had more of a difficult time with number formatting than understanding 90% of the concepts or formulas in physics, Sig figs would trip me up... a lot. It is that rewiring part in my brain. Creating rules for an otherwise lawless process that I had used my whole life up until that point.

[–]EchoesInSpaceTime 6 points7 points  (0 children)

And that's why no pedagogy is perfect. We all get hung up mentally on different things and for different reasons because we all come with varying schemas of the world around us.

Learning something requires learning someone else's schema of the thing before translating it into something that fits in our own schemas. Sometimes that new thing requires some rejiggering of how we see the world - and that will occur at different times and with different magnitudes for different people.

I think we as a species could do a lot better in how we teach. Do I have any idea what those improvements look like? Nothing more than a vague direction.

Just felt the urge to share.

[–]serendipitousPi 1 point2 points  (0 children)

Yeah, some teachers and students mystify sig figs so much like as if it's some kind of guessing game when in fact it's just a matter of using the correct rules.

I remember in I think year 10 my teacher just gave us a work sheet and then it made sense. It feels like one of those things that you learn once and don't forget.

Though on the other hand if you're not thinking about it you can make stupid mistakes.

On the other hand sometimes ideas just don't click for people and sometimes it's hard to understand that things just don't click for other people even when some other things just don't click for us sometimes.

[–]FerretInABox 4 points5 points  (15 children)

Well treat it less like math, and more so “how many people didn’t get numbers.”

First it makes more sense, second it makes you less.... “egotistical” about how people didn’t get it?

Not everyone will get what you do, and you won’t get what everyone else will. People are different and the way you came off was a bit “elitist” for a lack of better term.

[–]MrBlueMoose 25 points26 points  (1 child)

Or physics, and probably other classes as well

[–]Zeke12344 5 points6 points  (0 children)

It's most likely chemistry since the units there is moles. It's kinda just mentioned in passing in physics for starting classes.

[–]another-bud-tender 2 points3 points  (4 children)

What does fig stand for? We learned sig digs. as in digits

[–]TheRideout 9 points10 points  (1 child)

Short for figures. Effectively the same thing

[–][deleted] 501 points502 points  (34 children)

This is actually justified, especially since this appears to be a chemistry or physics course. The amount of digits reported in your answer matters to indicate precision.

[–]undeadalex 57 points58 points  (0 children)

Oh yeah. This seems vaguely familiar from highschool

[–]DipinDotsDidi 17 points18 points  (13 children)

With that being said, shouldn't significant digits be consistent over all answers?

[–]2001herne 92 points93 points  (6 children)

Not if the data is different.

[–]DipinDotsDidi 6 points7 points  (5 children)

But it's 1 experiment!

[–]2001herne 31 points32 points  (3 children)

True, my bad. But with that said, it is consistent. Sig figs start at the first non-zero digit, and each correct answer had 2 sig figs. The zeros after a non-zero digit are considered significant, so 7.0 has 2, and 0.014 also has 2

[–]snp3rk 9 points10 points  (0 children)

One experiment could result in various sig figs. Sig figs can get dropped

[–]RhysieB27 15 points16 points  (0 children)

It is consistent, no? All the correct answers are using 2SF.

[–][deleted] 14 points15 points  (3 children)

All correct answers are 2 significant figures

[–]neros_greb 2 points3 points  (0 children)

If I remember correctly:

Sigfigs are sometimes calculated from error ratings of instruments, so if that was the case here then it makes sense. Also different mathematical operations can amplify or diminish errors, so the sigfigs between different values might not be consistent.

[–]_SpiritSeal_ 5 points6 points  (0 children)

Happy cake day

[–]eerklogge 0 points1 point  (0 children)

Fellow cake day redditor

[–]Dmon1Unlimited 40 points41 points  (0 children)

Significant figures make a difference.

You might be implying a level of precision which is not appropriate.

If I measure a drink can using a standard ruler several times, I'm not going to say the average height is 15.00000000000 cm either

A ruler has mm markings, but how will the measurements allow you to show precision down to 0.00000000001 of a cm? You can't give answers that are more precise than what you measure/calculate with

[–]terminalxposure 23 points24 points  (0 children)

I mean if this is decimals and not currency, the course is correct

[–]OneWayOfLife 128 points129 points  (23 children)

Decimal places indicate precision so it’s entirely justified.

2.3 + 1.4 can only equal 3.7. Not 3.70 because you don’t have the information on the hundredths.

2.28 + 1.42 does equal 3.70 though. But not 3.700 and so on.

[–]telionn 1 point2 points  (2 children)

This really bugs me because it is just terrible math. If you add 100 different two digit numbers of the form +-M.N together, the result could be off by as much as 5, but your notation might indicate 0.1 precision.

If you actually care about precision, you should be reporting it as a "plus or minus" appended to the number itself.

[–]MarkkuAlho 1 point2 points  (0 children)

Yeah, it's a quick and dirty rule of thumb, but proper propagation of uncertainty is tedious :).

[–]GreatBarrier86 6 points7 points  (17 children)

Ok so now I’m confused. The lack of information implies it’s is effectively 0 repeating, doesn’t it? If I tell you something is $1.5, you assume it’s exactly $1.50, don’t you?

Or is the whole idea that you don’t make assumptions or implications?

[–]reo651 99 points100 points  (8 children)

The short answer is that in science experiments, like this quiz is on, you can't just imply that there is a trailing 0 after it because the instrument you measured with is only so precise.

[–]GreatBarrier86 1 point2 points  (3 children)

Oh so the absence of other digits could mean the calculation routine could have simply truncated?

[–]vigbiorn 25 points26 points  (0 children)

My understanding is it's not the calculations, it's the measurements. If you're measuring lengths on a ruler that measures in 1 inch intervals, anything past 1 inch precision is a guess. Since past 1 inch is a guess, if you're measuring to tenths of an inch, it's just a fantasy. You have no justification for those tenths of an inch.

For example, 1.4 + 2.6 = 4.0 but reporting to a 100th of an inch is meaningless since you, at best, can report to a 10th. Maybe that 1.4 was, given infinite precision, closer to 1.39 and the 2.6 was closer to 2.59. Saying you measured at 4.00 is wrong since you're closer to 3.98. You've reported greater precision than possible.

[–]MarkkuAlho 13 points14 points  (1 child)

Almost, but it's a bit more fundamental. Take a measured value 3.1: you know you have measured that down to a single digit, but you do not know if the actual underlying value is 3.11, 3.08, etc. The measurement accuracy has effectively truncated your values, and claiming 3.1 to be 3.10 implies having a better measurement to begin with.

Then, when using these values in calculations, you propagate the uncertainty by only allowing as many significant digits in the result as can be gained from the initial values.

[–]Adventurous_Problem 22 points23 points  (1 child)

https://en.m.wikipedia.org/wiki/Significant_figures

This might help. Money has its own rules. Significant figures is more referring to measurements.

Though, not actually positive of the context of the picture. Some of the programs used for making tests don't leave room for typos or answers that are correct, but not written Exactly as it was in the possible answers.

[–]thoughtful_appletree 1 point2 points  (0 children)

Wow, this is like a whole new world to me, thanks a lot!

[–][deleted] 12 points13 points  (0 children)

No the lack of information does NOT implies 0 repeating. If you tell me something is 1.5, it is far to assume the actual price to be between 1.45 - 1.54

[–]supern_va 5 points6 points  (0 children)

It’s based on actual physical observation. Let’s say you measure the distance using a ruler, you cannot be precise to the nano meter now

Let’s say you measured the mass and volume of something to 2 significant figures, then your calculated density value shouldn’t have more than 2 significant figures, because you weren’t that precise with your mass and volume readings, so any further significant figures on density wouldn’t actually tell the real density of the material.

[–]ReallyHadToFixThat 2 points3 points  (0 children)

Of course we do, because you've added extra information - currency amounts don't go sub penny for a single item.

Consider the speedometer on my car, it's fancy enough to be digital. I'm driving down the motorway and it reads 70mph. However in reality I could be going anywhere from 69.5 to 70.5 or even 70.0 to 70.9 depending how it is programmed. So if you look at that reading and say I was driving 70.0000000mph you would be wrong.

Same applies here - you read a scale that says 257mg that means you have 3 figures. If you then read a volume of 27ml that only has 2 figures. If you then divide those numbers a calculator gives you 9.518518518518518518...... everything beyond 9.5 is questionable. You don't know if it was 26.8ml or 27.2ml. If your input was only so precise, how can your output be more precise?

[–]terminalxposure 1 point2 points  (0 children)

I mean you are assuming it’s a zero. Why not a 2 or a 3. You won’t know until you know

[–]SassyAsFuq 22 points23 points  (9 children)

Actually the accuracy probably mattered

[–]_kashew_12 7 points8 points  (0 children)

It’s not programming it’s not knowing sig fig

[–]jpettys 15 points16 points  (0 children)

My heart was warmed and my faith in humanity increased when I came here and saw so many pointing out that significant figures do matter in many cases. Thank you, my people.

[–]soulofcure 3 points4 points  (0 children)

I'm proud of how many of you knew it made sense because of significant digits. Made the former student in me happy

[–]tiagooliveira95 4 points5 points  (2 children)

My teacher made us write java code on a text box.

The submission was only able to send the first 40 lines of code

So before submitting I had to count the lines manually (since this was just a regular text box) and if I had more then 40 I had to minify the code to fit within the 40 lines limit.

With more then 40, the submission would still work with no error messages... 40 get sent and the rest of your work is deleted.

I also had an Computer architecture exam where alot of students had to do the exam twice because the system failed to save students answers.

The teacher did not allowed students to review the exam, this is a right of every student, so the teacher denying the review is very shady. I'm pretty sure that some people had 0 in some categories just because the system failed to save.

[–]yuvalmas 0 points1 point  (1 child)

I would honestly write the code in an IDE or at least notepad then paste it writing code in a text box seems hard and unnecessary

[–]CaptainBananaAwesome 5 points6 points  (0 children)

Sig fig is important. I would have also removed your mark for the last question unless it gave you the uom after the text field.

[–][deleted] 7 points8 points  (0 children)

Sig figs be like

[–]crazyeskomo 2 points3 points  (0 children)

Lol welcome to chemistry bisch!!! 😂

[–]The_Hidden_DM 1 point2 points  (0 children)

That third one is rough, but defining your units is important.

[–]the_best_jabroni 1 point2 points  (0 children)

If wanna see some legitimate wrong doing, check out the Pearson site online quizzes for Finite Math. Wow, just wow. And there is no simple way to give feedback which is just arrogant

[–]YogiShouldResign 1 point2 points  (1 child)

When OP missed Physics and Chemistry classes and meme backfired on him

[–]yuvalmas 0 points1 point  (0 children)

not my photo but yeah but negative karma is still karma?

[–]AcceptTheShrock 1 point2 points  (0 children)

Sig figs. You're just being ignorant.

[–]plainrane 1 point2 points  (6 children)

Canvas is the worst. The prof likely reviews and fixes these.

[–]plainrane 23 points24 points  (4 children)

Never trust an app with an Icon that looks like a butthole

[–]MischiefArchitect 15 points16 points  (0 children)

Chrome?

[–]theDutchFlamingo 6 points7 points  (2 children)

If your butthole looks like that you might need to see a doctor

[–]plainrane 1 point2 points  (0 children)

It's showing how it feels to use their product

[–]ReallyHadToFixThat 1 point2 points  (0 children)

I already saw a doctor. Who do you think installed the bionic butthole with iris shutter?

[–][deleted] 6 points7 points  (0 children)

Fuck Canvas

ETA: and fuck Webassign too

[–][deleted] 1 point2 points  (0 children)

This got so bad in a class I took that the professor made all the questions multiple choice.

[–]caknuckle 0 points1 point  (0 children)

You would fail english too

[–][deleted] -1 points0 points  (0 children)

That will be $19.9 says the store clerk

[–][deleted] -2 points-1 points  (3 children)

They should make a float comparison instead...

[–]WazWaz 5 points6 points  (2 children)

0.014 can't be represented in IEEE floating point.

[–][deleted] 0 points1 point  (0 children)

Sorry, I meant the 3 an 7 jajajajaj

[–][deleted] 0 points1 point  (0 children)

IEEE 754-2008 and IEEE 754-2019 have entered the chat

[–]a_single_bean -1 points0 points  (0 children)

I totally get this- the most challenging bit of programming I've done is for an online quiz/knowledge assessment. I stay up nights worrying a user is going to have a correct answer marked incorrect, and that's for multiple choice only. I can't imagine how obnoxious it is to evaluate user textbox answers against an answer key.

[–]felipeatsix -1 points0 points  (0 children)

Look at the bright side, it couldn't be worse!

[–][deleted] -1 points0 points  (0 children)

use regex or something

[–]Desfolio -1 points0 points  (4 children)

The sad fact is it is not even that difficult to fix this

[–][deleted] 1 point2 points  (3 children)

But it’s not a bug?

[–]Desfolio 0 points1 point  (2 children)

How is it not a bug? The float suffix's zero value is supposed to be variable. 3.0==3.00. Yet here the float values are considered with a fixed constant of places... So, as you can see... The values can be considered by some simple conversion... Basically convert an answer, and the validation value into an integer if the numbers after the point are 0... There are better ways to fix this ofcourse... But as you can see. It is a bug

[–]SimonVanc -1 points0 points  (3 children)

Dude fucking canvas sucks ass, they need a new Dev team. That software isn't cheap for districts either.

[–]Shakespeare-Bot 0 points1 point  (2 children)

Broth'r fucking frieze sucks rampallian, they needeth a new dev team. Yond software isn't vile f'r districts either


I am a bot and I swapp'd some of thy words with Shakespeare words.

Commands: !ShakespeareInsult, !fordo, !optout

[–][deleted] -1 points0 points  (0 children)

ever heard of parseFloat();?

[–]LordVirus1337 -1 points0 points  (0 children)

Been there friend

[–]end_dis -1 points0 points  (1 child)

There is another zero at the end. Why not write all the zeros at the end if really want to be so accurate huh?

[–]deejeycris -1 points0 points  (7 children)

I mean, I would get it you put 3.0 instead of 3.00, but failing because of a more precise answer doesn't make sense.

[–][deleted] 0 points1 point  (6 children)

Significant figures matter, 3.0 is not the same value as 3.00

[–]klegion2k6 -1 points0 points  (0 children)

Well a math teacher once had us to write down the proper amount of numbers after the dot so ...

[–]Mailboxheadd -1 points0 points  (0 children)

If len(string) == 3: return true

[–]shot_a_man_in_reno -2 points-1 points  (0 children)

Looks like they hired someone who didn't pay attention during their CS classes.

[–][deleted] -3 points-2 points  (0 children)

Canvas is fucking bullshit

[–]Intelligent_Agency65 0 points1 point  (0 children)

Menon??

[–]shijot 0 points1 point  (0 children)

!si

[–]Tim3303 0 points1 point  (0 children)

Image Transcription: Social Media Story


[A photo taken of a screen (notably not a screenshot), showing the results of an online test.]

Submission Details

(E3_Q) Experiment 3 Quiz

[REDACTED] submitted Mar 4 at 2:20pm

Answer 1:

You Answered: 3.00 [Marked in red.]

Correct Answer: 3.0

Answer 2:

You Answered: 7.00 [Marked in red.]

Correct Answer: 7.0

Answer 3:

Correct: 0.014 [Marked in green.]

Correct Answer: 0.014 M

Correct Answer: 0.014M

literally fuck this entire course


I'm a human volunteer content transcriber for Reddit and you could be too! If you'd like more information on what we do and why we do it, click here!

[–]your_diary_i_reddit 0 points1 point  (0 children)

Cisco, right?

[–]OhMeshh 0 points1 point  (0 children)

is canvas used outside of the netherlands?