Can anyone help?

[Flumpy2012]

Please can anyone help?!
I'm sat sobbing over my open university assignment, I can't get hold of my tutor and it's due in next week.

I am struggling with scientific notation.

6.02 x 10 to the power 23 molecules in 18 grams, how many in 1 gram.

The fraction 3.09 x 10 to the power -9 over 0.02 x 10 to the power -9 in it's simplest form.

I am not stupid but I just cannot make sense of this. I don't want the answers but I want to understand how to work this out.

Any help is greatly appreciated.

Thank you xxx

[lljkk]

awww... did you sort it?
Well if you haven't by now maybe it's not cheating to give a little help.
Cheat & find an internet site to calculate for you?

So 6.02 x 10^23 in 18 grams, so how many in 1 gram...

Divide 6.02 by 18, no? It will be 3.something x 10^22 I think

(3.09 x 109) / (0.02 x 10(-9) ) = 10^18 x (3.09 / .02 )

because the 9 on top & the (-9) on bottom become ^18 on top when put together (but that is hard for me to explain without pencil & paper in front of you)

[dapoxen]

A quick google of "scientific notation" throws up some helpful web-pages which explain how it works
(www.mathsisfun.com/numbers/scientific-notation.html and www.chem.tamu.edu/class/fyp/mathrev/mr-scnot.html).

Incidentally, the powers in the 2nd question are both -9, so they cancel, leaving 3.09/0.02. And then I think (but am not at all sure) by 'fraction... ... in its simplest form' they want you to multiply top and bottom by 100 so you're got integers on the top and bottom.

[TrinitySky]

I am on the exact same course, and I've been having the same trouble also lol.. Which is how I got here !!! It's only the second part I've been having trouble with... The fraction.
I've still not quite got it 100% but I'm pretty sure that as above, the 10-9 cancel each other out, and then you'd multiply to the main numbers by 100 to give you 309 over 2. I think. lol.. If I'm wrong, someone please let me know. Flumpy, if you need any more study buddying, add me on facebook at facebook.com/trinitystar or email me at [email protected]
it's always handy to have someone on the same course as I don't really speak to many people on the student forums.