[anlb4]

now i am stuck again...i feel I should know this stuff..the problem is

243.5-87.1289=1.2/1.753-0.0473-5.4


express the result wityh the crrect number of significant figures..breaking it down I came up with 157.57/-3.69...well I know thts not right...the answer is-4.3x10to the 1 how did they get that  *delete me*!!!!!!!!!!

[movies]

Looks right to me.  Evaluate the fraction you have and you should get  something like -42.7.  You're limited to two significant figures,  so it's -43.  Then put it in scientific notation and you get 4.3 x 10¹.

Some scientific notation links:

http://janus.astro.umd.edu/astro/scinote/
http://www.nyu.edu/pages/mathmol/textbook/scinot.html
http://members.aol.com/profchm/sci_not.html