knowing how many sig figs to use
Moderators: Chem_Mod, Chem_Admin
knowing how many sig figs to use
If a problem uses a certain amount of sig figs, should all our work use that amount of sig figs, or should we round to the sig fig amount only for the answer?

 Posts: 5
 Joined: Thu Jul 11, 2019 12:17 am
Re: knowing how many sig figs to use
You can use different amounts of sig figs as you're working on the problem, however make sure you keep track of how many sig figs for your final calculation. If you are constantly rounding to 3 sig figs, for example, it is probable your answer may be inaccurate or far from the actual answer.

 Posts: 101
 Joined: Fri Aug 09, 2019 12:17 am
Re: knowing how many sig figs to use
I would suggest rounding to the correct amount of sig figs for the final answer and trying to keep the precise values on your calculator as you work through the problem, that way there is more accuracy.
Re: knowing how many sig figs to use
I remember in class him saying not to round till the very last step but in showing work he would round in the lecture slides to neatly show the steps since the focus in the recent lectures were not actual sig figs. I suggest doing this on homework as well

 Posts: 103
 Joined: Sat Aug 17, 2019 12:18 am
Re: knowing how many sig figs to use
I think in order to make your answers as accurate as possible, you shouldn't round to the correct number of significant digits until the very end. If you round with every step, your answer will gradually get farther and farther away from the actual answer, so I would say keep as many digits as possible until you reach the end of the problem. Then, pay attention to the number of sigfigs.

 Posts: 101
 Joined: Sun Sep 29, 2019 12:16 am
Re: knowing how many sig figs to use
To keep your work as accurate as possible, try not to round until the final answer. On the basis that you do round, keeping a certain number of significant figures should be enough to result in the final answer. For example, if the answer needs to have two significant figures, keeping four significant figures throughout your work will likely be enough (instead of maintaining, say, ten significant figures throughout).

 Posts: 108
 Joined: Sat Sep 28, 2019 12:15 am
Re: knowing how many sig figs to use
I would say when you are working on intermediate calculations, then have more numbers and at the end round to correct number because if you round to close in the intermediate calculations that can affect your final answer by a lot.

 Posts: 60
 Joined: Thu Feb 28, 2019 12:15 am
Re: knowing how many sig figs to use
Does anyone know how much sig fig answers are worth in the context of tests and exams? How many points will be deducted if sig figs are used incorrectly?
Re: knowing how many sig figs to use
You should keep as many sig figs as possible while you work on the problem in order to be the most accurate. Then at the end, you can round to the correct number!

 Posts: 51
 Joined: Sat Sep 07, 2019 12:19 am
Re: knowing how many sig figs to use
I would recommend only rounding to the correct amount of sig figs when you reach your final answer. I would keep the exact value when doing calculations.

 Posts: 100
 Joined: Thu Jul 11, 2019 12:16 am
Re: knowing how many sig figs to use
Eva Zhao 3B wrote:To keep your work as accurate as possible, try not to round until the final answer. On the basis that you do round, keeping a certain number of significant figures should be enough to result in the final answer. For example, if the answer needs to have two significant figures, keeping four significant figures throughout your work will likely be enough (instead of maintaining, say, ten significant figures throughout).
Thank you, I've been confused about this.
Re: knowing how many sig figs to use
I was recommended to keep as many digits as possible until the very end. This last test, our TA told us that he wasn't placing a heavy emphasis on sig figs so we shouldn't worry about it, but they might start counting it in the future.

 Posts: 105
 Joined: Sat Aug 17, 2019 12:18 am
Re: knowing how many sig figs to use
I think that it is proper to use the same amount of sig figs throughout the entire problem, so that there is consistency with each preceding calculation. Especially with given units, the sig figs in your final answer should likely match the amount of sig figs with these given numbers.

 Posts: 103
 Joined: Fri Aug 30, 2019 12:17 am
Re: knowing how many sig figs to use
Is it usually safe to have four decimal places for calculations and answers?

 Posts: 51
 Joined: Thu Jul 11, 2019 12:16 am
Re: knowing how many sig figs to use
You want to match the number of decimal places that correlates to the correct number of significant figures.

 Posts: 50
 Joined: Wed Sep 18, 2019 12:17 am
Re: knowing how many sig figs to use
For calculations you may use as many decimal places as you see fit to be accurate but its good to use your answer in the least number of sig figs in the question.
Re: knowing how many sig figs to use
Aman Sankineni 3E wrote:Is it usually safe to have four decimal places for calculations and answers?
For calculations I usually round to the nearest thousandth but once I get to the answer I make sure to match its sig figs to the # of sig figs used in the question :) I don't know if/how many points are taken off if we don't round the answer to the correct number of sig figs though :/

 Posts: 108
 Joined: Sat Jul 20, 2019 12:16 am
Re: knowing how many sig figs to use
Sig Figs are important and you should keep them in mind while you're doing a problem but only round at the end
Return to “SI Units, Unit Conversions”
Who is online
Users browsing this forum: No registered users and 1 guest