MacRumors Forums What is 58.629 to one significant figure?

 Nov 4, 2012, 02:38 PM #1 Intel Inside macrumors 6502   Join Date: Sep 2008 What is 58.629 to one significant figure? 50 or 60? __________________ My Photography Blog 0
 Nov 4, 2012, 02:41 PM #2 r.j.s Moderator emeritus     Join Date: Mar 2007 Location: Missouri It would be 60. 0
 Nov 4, 2012, 02:41 PM #3 stridemat Moderator     Join Date: Apr 2008 Location: Southampton, UK I would say 60. __________________ I support the MacRumors Blood Drive! 0
 Nov 4, 2012, 02:43 PM #4 Intel Inside Thread Starter macrumors 6502   Join Date: Sep 2008 Thanks guys, i think it's 60 too. trying to prove to someone that it is really 60! __________________ My Photography Blog 0
 Nov 4, 2012, 02:50 PM #5 macjram macrumors 6502a   Join Date: Dec 2008 I would say that from: 50-54: 1 sig fig would be 50 55-60: 1 sig fig would be 60 __________________ www.jonathanwho.com : student intern2010 Macbook Pro, iPhone 4S 0
 Nov 4, 2012, 02:55 PM #6 chown33 macrumors 603   Join Date: Aug 2009 The Wikipedia article has the conventional explanation, and links to articles on Rounding, etc.: http://en.wikipedia.org/wiki/Significant_figures 0
 Nov 4, 2012, 02:56 PM #7 Peace macrumors P6     Join Date: Apr 2005 Location: Space--The ONLY Frontier http://ostermiller.org/calc/significant_figures.html 0
 Nov 4, 2012, 06:44 PM #8 puma1552 macrumors 68040   Join Date: Nov 2008 sig figs are stupid as hell and serve little purpose in the real world that said, its 60 for your professor 2
 Nov 4, 2012, 07:08 PM #9 Rodimus Prime Banned   Join Date: Oct 2006 general rule 1-4 round down. 6-9 round up. 5 rounds to nearest even number. 1
Nov 4, 2012, 07:09 PM   #10
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Quote:
 Originally Posted by Rodimus Prime 5 rounds to nearest even number.
In computing, yes, but in maths I believe you round away from zero.
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 Nov 4, 2012, 07:10 PM #11 AlphaDogg macrumors 68040     Join Date: May 2010 Location: Boulder, CO 60 is one sig fig. 60. is 2 sig figs. 060 is 2 sig figs (not sure on this one) __________________ 15" 2.66GHz C2D uMBP | 13" 2.4GHz i5 MBP 500GB | '07 MacBook iPhone 6 64GB | iPhone 5 32GB | iPhone 8GB אין חשיש בקולורדו 0
Nov 4, 2012, 07:10 PM   #12
Rodimus Prime
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Quote:
 Originally Posted by puma1552 sig figs are stupid as hell and serve little purpose in the real world that said, its 60 for your professor
no they have a huge purpose in the real world. Big time in engineering.

Reason why is numbers past the point of what significant figures you have worthless and can not be trusted in any way shape or form. With out significant figures you end up with a fairly large amount of rounding error that can and will build up very quickly and really throw off your answer.
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Nov 4, 2012, 07:17 PM   #13
RITZFit
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Quote:
 Originally Posted by Rodimus Prime no they have a huge purpose in the real world. Big time in engineering.
Yup, especially when you start talking about machining precision and tolerancing, both of which will be driven by cost, application, and tooling capabilities.
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 Nov 5, 2012, 09:39 PM #14 Signal-11 macrumors 65816     Join Date: Mar 2008 Location: 2nd Star to the Right What about 54.999... to one sig fig? 0
Nov 5, 2012, 09:50 PM   #15
AustinIllini
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Quote:
 Originally Posted by AlphaDogg 60 is one sig fig. 60. is 2 sig figs. 060 is 2 sig figs (not sure on this one)
60 is one sig fig.
60. is two sig figs.
060 is one sig fig (leading zeros are never significant)

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Quote:
 Originally Posted by signal-11 what about 54.999... To one sig fig?
50
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Nov 5, 2012, 10:15 PM   #16
Signal-11
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Quote:
 Originally Posted by AustinIllini 50
What about 55? What does 55 round to?
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Nov 5, 2012, 10:21 PM   #17
AustinIllini
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Quote:
 Originally Posted by Signal-11 What about 55? What does 55 round to?

http://en.wikipedia.org/wiki/Rounding
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Nov 5, 2012, 10:26 PM   #18
Signal-11
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Quote:
 Originally Posted by AustinIllini depends on your standard. http://en.wikipedia.org/wiki/Rounding
Then why state unequivocally that 54.999... rounds down to 50?
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Nov 5, 2012, 10:31 PM   #19
dukebound85
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Quote:
 Originally Posted by puma1552 sig figs are stupid as hell and serve little purpose in the real world that said, its 60 for your professor
Obvious you are not an engineer lol

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Quote:
 Originally Posted by Signal-11 Then why state unequivocally that 54.999... rounds down to 50?
To me 54.9999999.... Rounds to 60 at 1 sig fig as 54.999999... ..is exactly the same as 55 mathematically
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Nov 5, 2012, 10:32 PM   #20
AustinIllini
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Quote:
 Originally Posted by Signal-11 Then why state unequivocally that 54.999... rounds down to 50?
A vast majority of standards maintain that 54.999 rounds down to 50. It's when a number is EXACTLY half way when things get hazy.

4.999 is like standing on your 49 yard line of a football field. Ultimately, however you slice it, you are closer to your own end zone. No matter what happens, 4.999 is closer to 0 than to 10.
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Nov 5, 2012, 10:33 PM   #21
puma1552
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Quote:
 Originally Posted by dukebound85 Obvious you are not an engineer lol[COLOR="#808080"]

Actually I am; I have not ever once seen anyone give two sharts about sig figs in industry.

Not once. Not once have I ever seen someone take 54 of something and decide it's better/more accurate to round that off to 50.
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Nov 5, 2012, 10:34 PM   #22
AustinIllini
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Quote:
 Originally Posted by dukebound85 Obvious you are not an engineer lol ---------- To me 54.9999999.... Rounds to 60 at 1 sig fig as 54.999999... ..is exactly the same as 55 mathematically
Okay, I misunderstood the original intent, but 54.9999999... is improper and should be written as 55, which rounds to 60 in almost every standard. I thought you literally meant 54.999

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Quote:
 Originally Posted by puma1552 Actually I am; I have not ever once seen anyone give two sharts about sig figs in industry. Not once.
You don't work in Pharmaceuticals. That being said, usually we don't argue 1 sig fig. it's usually at least three.
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Nov 5, 2012, 10:37 PM   #23
dukebound85
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Quote:
 Originally Posted by puma1552 Actually I am; I have not ever once seen anyone give two sharts about sig figs in industry. Not once. Not once have I ever seen someone take 54 of something and decide it's better/more accurate to round that off to 50.
Granted usually more precision is needed than 1 sig fig in practice

BUT.....

sorry if I doubt your claim that sig figs aren't important for engineering. I speak as an engineer myself and without sig figs, there would be big issues
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Nov 5, 2012, 10:41 PM   #24
AustinIllini
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Quote:
 Originally Posted by puma1552 Not once have I ever seen someone take 54 of something and decide it's better/more accurate to round that off to 50.
This discussion is an extreme simplification, and usually computers make a great deal of rounding decision, but I wasn't honestly thinking "what do we need to round to determine the stroke time of a control valve".

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Quote:
 Originally Posted by dukebound85 Granted usually more precision is needed than 1 sig fig in practice BUT..... sorry if I doubt your claim that sig figs aren't important for engineering. I speak as an engineer myself and without sig figs, there would be big issues
Exactly. Sig figs provide information regarding the accuracy of measurements. They penalize the user's application of inaccurate equipment. If I want to measure the distance my car travels in 5 minutes, it doesn't matter that I can measure time to 5 decimal places if my distance measurement only carries one significant figure.
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Nov 5, 2012, 10:44 PM   #25
Signal-11
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Quote:
 Originally Posted by AustinIllini A vast majority of standards maintain that 54.999 rounds down to 50. It's when a number is EXACTLY half way when things get hazy. 4.999 is like standing on your 49 yard line of a football field. Ultimately, however you slice it, you are closer to your own end zone. No matter what happens, 4.999 is closer to 0 than to 10.
The three elipses following the three nines is another way of stating an infinitely repeating series of 9s.

As dukebound stated, 54.999... rounds to 60.

Just a bit of math trolling.
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