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### When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:32 am**

by **Jose Robles 1D**

For instance, when finding mass ratios I would divide an assumed amount of Hydrogen by its atomic weight; should I divide by 1 or its actual weight of 1.007 (I've seen both actions performed in a discussion)? These questions tend to deal a lot with assumptions so insight would help me a ton.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:36 am**

by **eduardomorales5**

It is best to round by the end of the problem and keep the precision of numbers during the problem to reach a more accurate answer. If you round too early, you might get a slightly lower or higher answer than what is correct. I would keep it at 1.007 for the sake of accuracy.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:44 am**

by **Jose Robles 1D**

Makes sense, I wouldn't want to determine my empirical formula from a simple rounding off the top of my head. Thanks for the fast reply.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:44 am**

by **Ashley Kao 1H**

Yes, I agree! When finding the molar ratio, I would utilize the most precise atomic mass of all of the different elements. This will ensure that your answer is as close to accurate as possible. Once you complete this, then rounding or considering significant figures is necessary.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:46 am**

by **Salma Fawzi 4G**

it's better to round your final answer so your calculation can be correct. If you round each step of your problem, then your sig figs might be incorrect towards the end.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 8:55 am**

by **sbottomley3a**

It's a good rule of thumb to always round at the end of solving. That way, your numbers are as precise as possible and you don't lose anything important in the actual calculation portion.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 10:24 am**

by **Elizabeth Harty 1A**

If you are waiting to round your answer until the end of the problem, how do you know how may decimal places/sig figs to use?

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 1:26 pm**

by **Sanjana Borle 2K**

You should probably keep from rounding until the very end, then round; I believe that is the most accurate.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 1:44 pm**

by **Max Madrzyk Dis 4G**

you should be as accurate as possible when doing you calculations and then round at the very end to accommodate for sig figs.

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 1:48 pm**

by **Nathan Rothschild_2D**

in response to how to know how many sig figs to use in the end, you should use the question in order to determine the number of sig figs in the end. So if the question gives 3.48 grams then your final answer should be 3 sig figs because that's how many sig figs the question had

### Re: When should one start rounding in a problem?

Posted: **Fri Oct 04, 2019 5:04 pm**

by **MBouwman_4A**

Itâ€™s best to round at the very end of the problem once you have an answer so that you are more precise. Rounding during steps in the problem can result in errors.

### Re: When should one start rounding in a problem?

Posted: **Sat Oct 05, 2019 2:42 pm**

by **Celena Kim 2I**

Agree with the above! Rule of thumb is to round your answer only at the end to get the most precise and accurate answer. Otherwise, errors might be carried throughout the steps and affect your final answer.