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
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 $\displaystyle 9.02570\cdot10^{-18}$ . but im off to watch a few math videos to catch up.
Depending on the context there could be a point in writing the last zero.
Significance arithmetic - Wikipedia, the free encyclopedia
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
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.
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:
$\displaystyle 8.19\cdot 10^5l$Code:Write each metric measurement using the most appropriate prefix:
I obtain 819kl
$\displaystyle 67500 micro gram$
no idea... stuck
$\displaystyle 2.041\cdot 10^-8MV$
no idea... stuck
$\displaystyle 0.00002651 s$
=26.51 micro sec
$\displaystyle 130.9\cdot 10^-10mA$
no idea... stuck
$\displaystyle 9.5\cdot 10^6cm$
no idea... stuck
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
67.5 * 10^3 * 10^-6 g = 67.5 mg
2.041 * 10^-8 * 10^6 V
You continue!
Yes.
130.9 * 10^-10 * 10^-3 A
Continue.
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
last should have been $\displaystyle 9.5\cdot 10^6 cm$
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.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
$\displaystyle 7.2\cdot 10^4 kg to cg$
the prefix power change from 3 to -2 (down five)
so the power of ten is adjusted up 5 therefore $\displaystyle 7.2\cdot 10^4 kg$ = $\displaystyle 7.2\cdot 10^1 cg$
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)