A few sig fig problems?

hi i waswondering if you guys could help me with some sig figs and explain the rules to me :]





1) (18.35-17.85)(4.18)(389)





Round to 2 sig figs


2)0.001893


3)273.15

A few sig fig problems?
1. subtract/addition you must round to least decimal places (do not confuse this with sig figs)





18.35-17.85=0.50





(note it goes from 4 sf to 2 sf because we subtract and there are different rules here)





then plug in before you can round to sig figs





(0.50)4.18(389)=813.01=810 =8.2 x 10^2 ( 2sf )





2 s.f. due to 0.50 having 2 the others have 3








put the answer to sci notation the number





ex 2 sig figs 0.001893 --%26gt; 1.9 x 10^-3


273.15 --%26gt; 2.7 x 10^2





here use this to help





reconstruct the link





http://www.kentchemi


stry.com/links/Measureme


nts/calcswithsigfigs.htm
Reply:When adding and subtracting, your results cannot be more precise than any number you are using (ex: 32.32-43, since 43 is less precise you must round to the ones place and the answer would be: -10.68 BUT now round for sig figs and you get -11)





When multiplying and dividing, your results have to have the same number of sig figs as the numbers you are dealing with (ex: 54.4/23, since 23 has the fewest sig figs, you must count that one and you find it to contain 2 sig figs, therefore as an answer you roughly get 2.3625 BUT now round to the two sig figs and you get 2.4)
Reply:well for the first u do the math and answer with the lest sig ifgs... in this case its 3 cuz 389 and 4.18 have the least sig figs..





2. = 0


3. = 270





i dunno about number 2