Page 2 of 2 FirstFirst 12
Results 16 to 28 of 28

Math Help - Scientific notation

  1. #16
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    Quote Originally Posted by yeKciM View Post
    correct answer is \displaystyle \frac{(5.19\cdot 10^{-6})(8.3\cdot10^{5})}{2.07\cdot10^{4}} = 2.081 \cdot 10^{-4}


    to get it by calculator :

    enter 5.16 then pres "exp" than 6 than "-" (+/- probably is written) than multiply "*" then enter 8.3 than "exp" than 5 pres "=" , than divede ( / ) than 2.07 again "exp" and 4.... press "=" again (you can do it without "=" before dividing but if you need to write down on paper .... ) than you will get 0.000208101 so now press "FIX" or something like that (depending on type of calculator , can be F -> E .... or something ) than you will get  2.081 \cdot 10^{-4}
    thats a different problem

    you're partially correct as this needs to be rounded to sn 2.1x10^-4
    Follow Math Help Forum on Facebook and Google+

  2. #17
    Senior Member yeKciM's Avatar
    Joined
    Jul 2010
    Posts
    456
    Quote Originally Posted by pychon View Post
    thats a different problem

    you're partially correct as this needs to be rounded to sn 2.1x10^-4
    depending for which is this needed is depending how accurate it should be ... because this is "small number" (0.0002081) it can be rounded to 2.1 on power of (-4) because this is close to it... when you round numbers you do it so that number after which you want to round (you say that is accurate for your need ... ) if number after that one like in this example is above 5 than that number is up by one ... if it was instead of 0.000208 it was 0.000202 than you will round it to 0.0002 so it means if is under 5 it stay there but if is more than 5 can be rounded to up by one... but that is depending on your needs ...

    if you had capacitor 0.000000017 F you can't round that to 0.00000002 F because that will make big difference
    Follow Math Help Forum on Facebook and Google+

  3. #18
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    Thanks for the help and corrections with this... one problem left on this sheet then two more pages of sn/en word problems and unit conversion :\ ; should have posted in univ maths.

    Last problem is find the reciprocal of 9.02570\cdot10^{-18} . but im off to watch a few math videos to catch up.
    Follow Math Help Forum on Facebook and Google+

  4. #19
    Senior Member yeKciM's Avatar
    Joined
    Jul 2010
    Posts
    456
    Quote Originally Posted by pychon View Post
    Thanks for the help and corrections with this... one problem left on this sheet then two more pages of sn/en word problems and unit conversion :\ ; should have posted in univ maths.

    Last problem is find the reciprocal of 9.02570\cdot10^{-18} . but im off to watch a few math videos to catch up.
    by hand or calculator ? just enter value and than you have mark written as "1/x" (probably is activated with that "2nd F" ) and you will get the reciprocal value
    P.S there is no point in writing that last zero
    Follow Math Help Forum on Facebook and Google+

  5. #20
    MHF Contributor undefined's Avatar
    Joined
    Mar 2010
    From
    Chicago
    Posts
    2,340
    Awards
    1
    Quote Originally Posted by yeKciM View Post
    P.S there is no point in writing that last zero
    Depending on the context there could be a point in writing the last zero.

    Significance arithmetic - Wikipedia, the free encyclopedia
    Follow Math Help Forum on Facebook and Google+

  6. #21
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    anyone around? need some major help with a few questions if someone wouldn't mind dedicating an hour... i've been swamped with things here. I have about 20 questions left in this assignment, taken notes, watched videos and still stumped. Questions are unit/metric conversion....
    Follow Math Help Forum on Facebook and Google+

  7. #22
    MHF Contributor undefined's Avatar
    Joined
    Mar 2010
    From
    Chicago
    Posts
    2,340
    Awards
    1
    Quote Originally Posted by pychon View Post
    anyone around? need some major help with a few questions if someone wouldn't mind dedicating an hour... i've been swamped with things here. I have about 20 questions left in this assignment, taken notes, watched videos and still stumped. Questions are unit/metric conversion....
    Just post new threads, limit 1 question per thread or a small number of related questions per thread, I'm a bit predisposed but someone should be around to help out. Basically it's just common sense with posting but here are the rules

    http://www.mathhelpforum.com/math-he...ng-151418.html
    Follow Math Help Forum on Facebook and Google+

  8. #23
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    That's a bit too much... i will not sit here typing out new threads in the forum and flood it with each problem... some problems are trival, but my mind has been wracked with other things. It's 1am here and class in 6 hrs. So anyone who knows metric / unit conversion is welcomed to help. (I thought there was a "live" chat on this forum?)
    Follow Math Help Forum on Facebook and Google+

  9. #24
    MHF Contributor undefined's Avatar
    Joined
    Mar 2010
    From
    Chicago
    Posts
    2,340
    Awards
    1
    Quote Originally Posted by pychon View Post
    That's a bit too much... i will not sit here typing out new threads in the forum and flood it with each problem... some problems are trival, but my mind has been wracked with other things. It's 1am here and class in 6 hrs. So anyone who knows metric / unit conversion is welcomed to help. (I thought there was a "live" chat on this forum?)
    Oh yeah the live chat doesn't work since a forum upgrade a little while back. Well I use the same approach with basically all unit conversions, I did one just a bit ago

    http://www.mathhelpforum.com/math-he...tml#post555343

    also this one

    http://www.mathhelpforum.com/math-he...tml#post554018

    Basically just write all units explicitly and make sure they cancel to give the desired end units. If it's simple enough you can be less explicit, but writing everything down carefully helps prevent mistakes, in my experience.
    Follow Math Help Forum on Facebook and Google+

  10. #25
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    Quote Originally Posted by undefined View Post
    Oh yeah the live chat doesn't work since a forum upgrade a little while back. Well I use the same approach with basically all unit conversions, I did one just a bit ago

    http://www.mathhelpforum.com/math-he...tml#post555343

    also this one

    http://www.mathhelpforum.com/math-he...tml#post554018

    Basically just write all units explicitly and make sure they cancel to give the desired end units. If it's simple enough you can be less explicit, but writing everything down carefully helps prevent mistakes, in my experience.

    Though, none of it is making sense nor sticks... my brain is flooded. I've done the supplement work, taken notes, watched videos, read my univ pages and worksheets, it's simple math just stressed out. grrr


    Example:
    Code:
    Write each metric measurement using the most appropriate prefix:
    8.19\cdot 10^5l

    I obtain 819kl


    67500 micro gram

    no idea... stuck


    2.041\cdot 10^-8MV

    no idea... stuck


    0.00002651 s

    =26.51 micro sec


    130.9\cdot 10^-10mA

    no idea... stuck


    9.5\cdot 10^6cm

    no idea... stuck
    Last edited by pychon; September 6th 2010 at 11:11 PM.
    Follow Math Help Forum on Facebook and Google+

  11. #26
    MHF Contributor undefined's Avatar
    Joined
    Mar 2010
    From
    Chicago
    Posts
    2,340
    Awards
    1
    Quote Originally Posted by pychon View Post
    Though, none of it is making sense nor sticks... my brain is flooded. I've done the supplement work, taken notes, watched videos, read my univ pages and worksheets, it's simple math just stressed out. grrr


    Example:
    Code:
    Write each metric measurement using the most appropriate prefix:
    8.19\cdot 10^5l

    I obtain 819kl
    819 kl is fine, but I think the question isn't very clear about the "most appropriate prefix". Should 0.05 metres be 5 cm or 50 mm? Of course it's subjective.

    You edited your post, so

    Quote Originally Posted by pychon View Post
    67500 micro gram

    no idea... stuck
    67.5 * 10^3 * 10^-6 g = 67.5 mg

    Quote Originally Posted by pychon View Post
    2.041\cdot 10^-8MV

    no idea... stuck
    2.041 * 10^-8 * 10^6 V

    You continue!


    Quote Originally Posted by pychon View Post
    0.00002651 s

    =26.51 micro sec
    Yes.

    Quote Originally Posted by pychon View Post
    130.9\cdot 10^-10mA

    no idea... stuck
    130.9 * 10^-10 * 10^-3 A

    Continue.

    Quote Originally Posted by pychon View Post
    9.5\cdot 10^6

    no idea... stuck
    There are no units here.

    There's probably a table like this in your book already, but if it helps,

    http://en.wikipedia.org/wiki/SI_prefix
    Follow Math Help Forum on Facebook and Google+

  12. #27
    Junior Member
    Joined
    Feb 2010
    Posts
    47
    last should have been 9.5\cdot 10^6 cm


    Have the prefix table memorized... i guess i'm falling short how to convert them properly.

    Text from my supplement:
    When the measurement is already in scientific notation, the power of ten in raised or lowered to offset the change that is made to the prefix.
    Example:
    convert
    7.2\cdot 10^4 kg to cg
    the prefix power change from 3 to -2 (down five)
    so the power of ten is adjusted up 5 therefore 7.2\cdot 10^4 kg = 7.2\cdot 10^1 cg
    Having a hard time understanding that, especially when both prefixes are between centi to pico.




    I don't see how you got:
    67.5 * 10^3 * 10^-6 g = 67.5 mg
    Follow Math Help Forum on Facebook and Google+

  13. #28
    MHF Contributor undefined's Avatar
    Joined
    Mar 2010
    From
    Chicago
    Posts
    2,340
    Awards
    1
    Quote Originally Posted by pychon View Post
    last should have been 9.5\cdot 10^6 cm


    Have the prefix table memorized... i guess i'm falling short how to convert them properly.

    Text from my supplement:


    Having a hard time understanding that, especially when both prefixes are between centi to pico.




    I don't see how you got:
    67.5 * 10^3 * 10^-6 g = 67.5 mg
    Your book says 7.2 * 10^9 cg right?

    Anyway I recommend taking a step back here. What is 1 km? It is 1 * 10^3 m. The prefix simply multiplies your quantity by some predefined power of 10.

    So for example 67500 micrograms, I rewrote as 67.5 * 10^3 micrograms, then 67.5 * 10^3 * 10^-6 grams, then 67.5 * 10^-3 grams, which is 67.5 mg

    Remember a^b * a^c = a^(b+c)
    Follow Math Help Forum on Facebook and Google+

Page 2 of 2 FirstFirst 12

Similar Math Help Forum Discussions

  1. scientific notation
    Posted in the Calculators Forum
    Replies: 0
    Last Post: September 23rd 2009, 02:40 PM
  2. scientific notation
    Posted in the Algebra Forum
    Replies: 2
    Last Post: May 23rd 2008, 06:54 AM
  3. Scientific Notation
    Posted in the Algebra Forum
    Replies: 3
    Last Post: May 23rd 2008, 06:01 AM
  4. Scientific Notation
    Posted in the Algebra Forum
    Replies: 13
    Last Post: April 1st 2007, 11:59 AM
  5. Scientific notation
    Posted in the Algebra Forum
    Replies: 1
    Last Post: December 28th 2006, 10:24 PM

Search Tags


/mathhelpforum @mathhelpforum