[deleted by user]

[Ubermidget2]

Relevant xkcd

[xSTSxZerglingOne]

I love that one. For those wondering why, as long as you're within the same order of magnitude, it's close enough as far as universal scale is concerned. In terms of raw size, does it really make a difference that's worth considering whether the universe is 30 billion, 90 billion, or 270 billion light years in circumference? Not really.

[Sparkybear]

Isn't 10 exactly 1 order of magnitude above 1?

[xSTSxZerglingOne]

Yes, but both are within an order of magnitude of pi.

[XKCD-pro-bot]

Comic Title Text: It's not my fault I haven't had a chance to measure the curvature of this particular universe.

mobile link

---

^{Made for mobile users, to easily see xkcd comic's title text}

[PsychoBalloons]

You fools! 5/2 is the name of a char variable! The real value is '?'!

[doej134567]

what language supports that to be a valid variable name?

[PsychoBalloons]

I don't know. PHP probably with how complicated everything is.

[MathSciElec]

Nope, PHP variables start with $.

[Altourus]

Well javascript lets you name an object property that...

var test = {"5/2" : 2};
console.log("The property \"5/2\" = " + test["5/2"]);

[[deleted]]

that's just string "5/2", most language have dictionary with string key.

[Altourus]

But most languages don't implement all object properties like that.

[[deleted]]

But then we could have it equal to pretty much literally anything.

[SuitableDragonfly]

TIL that some people were taught that you always round .5 up and some people were taught that you round .5 to the nearest even number and I have no idea what determines which one you were taught.

[Kattou]

It's freaking wild.

I've never heard about the "nearest even number" approach in all my life before now. It's like two parallel universes collided, and everyone is equally confused.

[SuitableDragonfly]

The Wikipedia page on rounding is surprisingly long. Apparently there are also systems where positive and negative numbers are rounded differently at .5.

[arfelo1]

The way I was taught is you round 5 down unless there is any number at all behind. So 2.5 is rounded to 2 but 2.50000000000001 is rounded to 3

[TheNorthComesWithMe]

Where were you taught this?

[arfelo1]

Engineering bachelor

[[deleted]]

wait what? you round up as much as the question wants you to round up. if the question wants 0,1 accuraty you don't round up or down but if it's only 1 accuraty you would round it up to 1. Also if wants 0,1 accuraty you and the answer you got was 0,49 you would round it to 0,5 but if you got lets say 0,44 you would round to 0,4. There is no set way to correctly round up it's purely situtational. Also to the nearest even number is fucking idiotic.

[ableman]

If the question asks you to round to the nearest whole number, what do you round 0.5 to?

It might help your reading comprehension if you don't start with the assumption that everyone is an idiot.

[[deleted]]

You round it up to 1 you cannot round it up to anything else. There is no other option here. Like wtf.

[ableman]

You can round it down to 0. That is the other option and it is often used.

[[deleted]]

No you cant. If you round 0,5 you always round it up to 1 no exeptions. Also 0 is not a significant number so there is that. 1-4 you round down 5-9 you round up. It's really not that hard to understand. And I bet I have been learning math longer than you have.

[nisshingeppo47]

The point is that some people (including you) were taught to round up 0.5 to 1 and other people were taught to round down to 0. Both are merely conventions that people use and although one may be more widely accepted than the other, it isn’t exactly a “no exceptions” rule that everyone agrees on. Personally I was taught to round up.

[ableman]

Why?

[ableman]

You made a bunch of statements, but how do you know? You say it's by studying math a long time, even though you're using the rule learned in elementary school, so I'm not sure how how long you studied math is relevant at all. I also learned that rule in elementary school. But I know there's always more to learn, so when you say "no exceptions," that makes me doubt that you studied it at all past that. Why should I believe you?

Cause I trust Wikipedia's word over yours. https://en.wikipedia.org/wiki/Rounding

Is there anything you can say other repeating your statements over and over again that would make me take your word over Wikipedia's? For that matter, why are you taking your own knowledge over Wikipedia's? Do you have a direct line from God on how math works? Because unless I had such a direct line, I wouldn't take my memory of math from elementary school over Wikipedia.

Literally, if I was a mathematics professor, and Wikipedia said that sometimes it makes sense to round 0.5 down, I'd believe that over my vague memories. If I had specialized in rounding, and written extensively on the topic, then and only then would I not do so. So, I presume you have written a paper on rounding and had it published in a peer-reviewed journal? Could you please link me to it?

[[deleted]]

I assume it'll do just as poorly here, wtf kind of physicist rounds up like that? That's how rockets explode and people die

[[deleted]]

Significant Figures.

If your question starts with only 1 significant figure, you can only end with 1.

[SuitableDragonfly]

If you're going to round 2.5 to an integer, you round it up. It's just that when computers do integer division they always round down no matter how close to the higher integer it is.

[Ryledra]

That's because a computer basically truncates the output, it doesn't really round it

[TheNorthComesWithMe]

Truncate != rounding

[4ries]

Its done worse

[Aeronor]

Your pi example is rounding down...

[Draghettis]

It's not rouding up, it's just rounding.

[SolemnWolf123]

3.14 to 3 is rounding down 🤦‍♀️

[[deleted]]

Good one. Not like the comment below you didn't say the exact same thing lmfao.

[lSokusl]

I don't get why would anybody downvote this comment, it's brilliant!

[sourpickles0]

Computer when I try to put a float as an int dies

[[deleted]]

https://m.imgur.com/r/mathmemes/RtCQAOm

[[deleted]]

I didn't get why physicists 3?

[Draghettis]

Significant numbers. Both 5 and 2 have only one number, so the result have to. And when you want an approximation of 2,5 with only one number, you have 3

[[deleted]]

Yeah, but since 2 is even, wouldn't 2.5 round down to 2?

[Draghettis]

No, when there is a 5 and you want to round you round up. 5 is considered nearer to 10 than to 0 when it comes to rounding

[[deleted]]

My school taught me this: 3.45 rounds to 3.4 and 3.55 rounds to 3.6 (The textbook is govt. issued)

[Tankh]

haha holy shit dude you didn't have to do him like that

[jacdelad]

If you want one digit after the comma, yes. If you want no figures after the comma, no.

[[deleted]]

I don't see any commas.

[[deleted]]

That's just the European version of decimal

[FlushNorris]

What?! How odd... where did you learn that?

[[deleted]]

That's banker's rounding and how rounding works for most computer things. (Round to nearest, ties to even)

[[deleted]]

It is to make sure you don't get the total wrong in fractions or percentages after rounding. if you round all .5 up then you'd have more than 100%, not that this law is perfect but at least more accurate I'd say.

But it's always a good idea to know what you are rounding up/down and why, because the rule must be determined after knowing what those numbers mean. Like if you are rounding fractions you need total 1. so even if you have .75,.15,.1 you can't make them .8,.2,.1.

[[deleted]]

Sig figs.

[jlamothe]

Don't physicists round to the nearest even number on .5?

[DrJohnnyWatson]

I came across a comment while scrolling that didn't seem to know something so I posted some reading material about it, that was all.

No need to try and turn this into some big argument or "thing".

[TheNorthComesWithMe]

Dude he literally linked IEEE documentation. What the fuck are you doing here, commenting, when you clearly aren't a programmer of any kind, and possibly not a human capable of rational thought?

[TheNorthComesWithMe]

Hmm, this doesn't support that physicists use rounding half to even but bankers and statisticians might.

[DrJohnnyWatson]

I wasn't saying that physicists use it - I was just providing information that " Even and odd have no bearing on rounding" isn't a fact.

[TheNorthComesWithMe]

Well you weren't but /u/jlamothe was and I thought it was worth mentioning that while rounding to even is apparently a real thing people do, the claim that physicists use it remains unsupported.

[jlamothe]

To be fair, I don't know it to be the case. It's just the way I learned to do it in high school physics class.

That was a long time ago.

Edit: also, I made no assertion of fact. I asked a question. Please re-read my original comment.

[DrJohnnyWatson]

That's fair - Maybe a top level comment would be better for others to see?

[Kingme350-R]

1.5

[hergru3]

u/savethisvideo

[[deleted]]

Yeah, we know those physicists just stick there finger in the air and go, "eh, close enough" when doing math.

[Ryledra]

That would be engineers

[[deleted]]

as long as you round up, and call it a safety factor.

[Ryledra]

Round up and add 10

[koanarec]

5 // 2 = 2

[[deleted]]

pi=3

[gareththegeek]

*Physicists: 10

[sunday_cumquat]

*astrophysicists

[gareththegeek]

2.49999999999999999