Do sig figs normally change the final answer significantly?

[kenhung123]

When doing calculations, lets say I used 2-3 sig figs instead of the full answer in calculator, generally, does it change the final answer to a point where it is wrong?

In the exam, is there a range of numerical answers or only a set answer which comes from only the calculator full values?

Sorry, I know I am a bit paranoid about this but I really don't want to drop marks on this!

[kyzoo]

My Chem teacher said that both the "calculator full" value and the "rounded to significant figures" value will be marked correct. But personally I would just go with the "calculator full" value. From comparing my answers to Methods prac exams to the corresponding solutions, I have learned that there can be quite a significant difference between the two values.

[physics]

do all the calculations fully but give the final answer in the number of significant figures they ask you.

[akira88]

Yeah what I do is use all the full numbers and only round it off into significant figures for the result, but if that result is needed for the next question, I will use the full number of it, not the significant figure.
Significant figures are stupid!

[the.watchman]

Yeah what I do is use all the full numbers and only round it off into significant figures for the result, but if that result is needed for the next question, I will use the full number of it, not the significant figure.
Significant figures are stupid!

Agreed, it's safest to work as accurately as possible throughout until the very end

[kenhung123]

So when you write down on paper the steps (not final answer), do you write sig figs or heaps of decimal places?
Only thing I am a bit worried is if I erased the full answer which is required in next question, and I am only left with 3 sig figs from last question.

[physics]

So when you write down on paper the steps (not final answer), do you write sig figs or heaps of decimal places?
Only thing I am a bit worried is if I erased the full answer which is required in next question, and I am only left with 3 sig figs from last question.

if you set the working out for the questions then it wouldnt take long to place them in the calc again or ideally just don;t erase ur asnwer in the first place

[superflya]

u can always store and recall when needed.

[Gloamglozer]

So when you write down on paper the steps (not final answer), do you write sig figs or heaps of decimal places?
Only thing I am a bit worried is if I erased the full answer which is required in next question, and I am only left with 3 sig figs from last question.

As a rule of thumb, I always kept everything to four decimal places until the final step where I rounded it off to the correct amount of significant figures.

In my opinion, four decimal places (if you're using decimals) is more than enough for VCE Chemistry.

[Studyinghard]

tbh sig figs would probably be the least of your worries in an exam. Max you would lose is 1 mark out of the whole paper. The time taken to figure out sig. figs for each and every question (unless your just naturally good at it) could be better used on answering other questions.

[qshyrn]

according to a uni chem textbook(silberberg) , you should have an extra 2 sigfigs in all steps except the last one.
my teacher said this isnt correct though, so im just sticking to what she says and giving the right no. of sig figs FOR EACH STEP, but keeping the values on calc

[kenhung123]

I generally hear people say on paper, all values should be correct sig figs but in calc, use most accurate answer.

I think the best solution is to write down the final answer to like 5 numbers after the first number e.g. 0.0000152313123958=0.0000152313 (or maybe less) and then next line do the sig figs so when I actually need the accurate answer I can get it?

[Gloamglozer]

tbh sig figs would probably be the least of your worries in an exam. Max you would lose is 1 mark out of the whole paper. The time taken to figure out sig. figs for each and every question (unless your just naturally good at it) could be better used on answering other questions.

I know it's only 1 mark, but should the odds be against you, you would really kick yourself if you were only 1 mark off the next highest grade.

[Nomvalt]

Yeah what I do is use all the full numbers and only round it off into significant figures for the result, but if that result is needed for the next question, I will use the full number of it, not the significant figure.

Same.

Significant figures are stupid!

yeah, like if you were to go 7 ml of solution X 3, you would get 21 but and then you've have to round that to 20, which is weird...

[kyzoo]

The time taken to figure out sig. figs for each and every question (unless your just naturally good at it) could be better used on answering other questions.

It only takes like 5 seconds to figure it out

my teacher said this isnt correct though, so im just sticking to what she says and giving the right no. of sig figs FOR EACH STEP, but keeping the values on calc

I agree with this.