What does 0.4999... round to?

Syringer

Lifer
Aug 2, 2001
19,333
2
71
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..
 

So

Lifer
Jul 2, 2001
25,921
14
81
since .4999.... = .5 and .5 rounds to 1 then it's one. /thread.

Why does .49999.... = .5?

Becaues .99999...= 1 and 1 - .5 = .5
 

Syringer

Lifer
Aug 2, 2001
19,333
2
71
What I'm really interested in are people who vote for either the 2nd or 3rd choices.
 

mugs

Lifer
Apr 29, 2003
48,924
45
91
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

Ok, let me get this straight...

You believe .999... = 1 like any sane person does
You believe that .4999... "technically" = .5
And yet you think .4999... is smaller than .5

... :confused:
 

Leros

Lifer
Jul 11, 2004
21,867
7
81
Originally posted by: So
since .4999.... = .5 and .5 rounds to 1 then it's one. /thread.

Why does .49999.... = .5?

Becaues .99999...= 1 and 1 - .5 = .5

QFT

/thread

if you disagree, go take another math class.
 

biggestmuff

Diamond Member
Mar 20, 2001
8,201
2
0
You don't just round numbers to whatever you feel like. You have to set a standard; round to the nearest ones place or round to the nearest one hundredths place.
 

QED

Diamond Member
Dec 16, 2005
3,428
3
0
Originally posted by: mugs
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

Ok, let me get this straight...

You believe .999... = 1 like any sane person does
You believe that .4999... "technically" = .5
And yet you think .4999... is smaller than .5

... :confused:


Well, there is a branch of mathematics which would say that you can have two real numbers be simultaneously equal and inequal. It's all in how you define things.

The concept of rounding arises naturally out of mathematics, but the supposition that numbers exactly halfway between sucessive integers get rounded up is about as arbitrary and unnatural as you can get.
 

iamaelephant

Diamond Member
Jul 25, 2004
3,816
1
81
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

Do you not know what the "=" sign means? It mean EQUALS, meaning that 0.499... is EXACTLY THE SAME NUMBER as 0.5, so why would it round to anyone other than what 0.5 rounds to, ie 1. Anyone with half a brain knows that if 0.999...=1 then 0.4999 rounds to 1.
 

Rayden

Senior member
Jun 25, 2001
790
1
0
Originally posted by: iamaelephant
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

Do you not know what the "=" sign means? It mean EQUALS, meaning that 0.499... is EXACTLY THE SAME NUMBER as 0.5, so why would it round to anyone other than what 0.5 rounds to, ie 1. Anyone with half a brain knows that if 0.999...=1 then 0.4999 rounds to 1.

He speaks the truth.

0.4999... is not any amount smaller than .5. If .5 rounds up to 1, then any other number that is EQUAL must also round to 1.
 

b0mbrman

Lifer
Jun 1, 2001
29,471
1
81
I round 0.499... to 0, but then again, I round 0.5 to 0 as well.

Now, 1.4999...? That's 2...
 

Howard

Lifer
Oct 14, 1999
47,989
10
81
For rounding digits whose value is 5, I believe the convention is to round up if the preceding digit is odd and round down if it's even. e.g. 0.5775 to 3 sig. digits would be 0.578 while 0.5765 would be 0.576.

So if you consider 0 to be even (it certainly isn't odd), then 0.5 ~= 0.
 

Tiamat

Lifer
Nov 25, 2003
14,074
5
71
0.4999... is 0.500... for all intents and purposes. If you consider zero an even decimal, then you round down. Therefore, 0.49999... or 0.5000... is equivalent to zero upon rounding. This method is used when you are dealing with a data set in which you are making judgements based on statistics.

If you want to do it the "grade-school" way, always round up.

Howard beat me.
 

iamaelephant

Diamond Member
Jul 25, 2004
3,816
1
81
Originally posted by: Tiamat
0.4999... is 0.500... for all intents and purposes.

People have to stop making that mistake. Please don't qualify that statement with "for all intents and purposes." 0.4999... is 0.5. End of story.
 

Tiamat

Lifer
Nov 25, 2003
14,074
5
71
Originally posted by: iamaelephant
Originally posted by: Tiamat
0.4999... is 0.500... for all intents and purposes.

People have to stop making that mistake. Please don't qualify that statement with "for all intents and purposes." 0.4999... is 0.5. End of story.

I used the phrase because I wasnt sure if using the elipses was good enough for this crowd, or if I had to actually spell out trailing 9's. (Usually I use the bar over the 9's but I dunno how to do this in html).

Also, .4999... = 0.500... not just 0.5. The trailling 9's notation I used denotes infinite significant figures, so, its equivalent has to also have infinite significant figures.
 

Howard

Lifer
Oct 14, 1999
47,989
10
81
Originally posted by: iamaelephant
Originally posted by: Tiamat
0.4999... is 0.500... for all intents and purposes.

People have to stop making that mistake. Please don't qualify that statement with "for all intents and purposes." 0.4999... is 0.5. End of story.
It's not like Tiamat said that there could be some way 0.4999... is equal to 0.5.
 

Dritnul

Senior member
Jan 9, 2006
781
0
0
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

but saying that it equals .5 which equals one is rounding twice which kinda makes rounding extremely vague
 
Nov 3, 2004
10,491
22
81
Originally posted by: Dritnul
Originally posted by: Syringer
I believe .999... = 1 like any sane person does (uh-oh), but I'm not really sure where to go with this one. On the one hand it technically is equal to .5 which rounds to 1, but if it's just ever so smaller than .5, which could also be the case, then it'd be 0..

but saying that it equals .5 which equals one is rounding twice which kinda makes rounding extremely vague

.999... =1, no rounding required
 

Dritnul

Senior member
Jan 9, 2006
781
0
0
well hell i mean with the logic in this thread ......
.226 rounds to .25 which rounds to .5 which rounds to 1
therefore .226=1