Rounding

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Shreya Patel- 2D
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Rounding

Postby Shreya Patel- 2D » Thu Oct 08, 2020 7:43 pm

When should we round our answer in a problem? For example, if it's a two step process, is it okay to round within the problem?

Sahaj Patel Lec3DisK
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Re: Rounding

Postby Sahaj Patel Lec3DisK » Thu Oct 08, 2020 7:50 pm

I assume you are talking about rounding sig figs. In that case, you should round your final answer. Until then, use numbers that are exact as possible.

Q Scarborough 1b
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Re: Rounding

Postby Q Scarborough 1b » Thu Oct 08, 2020 8:20 pm

Like what was said above, you should wait to round until the final answer. If you round before then, especially if the question has many steps, you can cause your answer to be skewed.

Brenda Silva 1B
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Re: Rounding

Postby Brenda Silva 1B » Thu Oct 08, 2020 10:40 pm

When solving a problem with multiple steps, such as a two step problem, try using the exact values throughout your calculations and only round your final answer, this would allow you to have an accurate result.

Darren1j
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Re: Rounding

Postby Darren1j » Fri Oct 09, 2020 11:37 am

Some elements of the periodic table have 4 sig figs as their molar mass and others have far more. When calculating the molar mass of a compound, how many sig figs should there be or number be rounded to?

George Hernandez 3I
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Re: Rounding

Postby George Hernandez 3I » Fri Oct 09, 2020 11:56 am

If it's not too confusing, try to use the most exact values as you possibly can and round at the end. This way, you won't have much dispairity to the actual answer. If you round your values throughout the problem, as you work through it, you may expect a solid whole number at some point but actually calculate 2.8, so you'll have to assume that it's '3' that you're looking for.

Aria Movassaghi 1A
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Re: Rounding

Postby Aria Movassaghi 1A » Fri Oct 09, 2020 12:03 pm

For me, the easiest way is to use exact numbers all the way until the final answer and then round that answer. This way, you don't have to worry about your final answer being slightly off.

Chem_Mod
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Re: Rounding

Postby Chem_Mod » Fri Oct 09, 2020 12:04 pm

Please do not round until the end! If you are using a calculator it should be fairly easy to store the values.

Sara_Lim_2C
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Re: Rounding

Postby Sara_Lim_2C » Fri Oct 09, 2020 12:09 pm

A friend of mine heard this rounding rule in her chemistry class (not at UCLA):

"If the digit removed is 5, the preceding number increases by 1 if it is odd and remains the same if it is even: 17.75----->17.8; 17.65----->17.6"

Neither of us had ever heard of it before, has anyone else? Is this a widely used rule or are there just certain institutions that might use it?

Jason_Glass_2L
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Re: Rounding

Postby Jason_Glass_2L » Fri Oct 09, 2020 12:46 pm

You are probably going to want to keep the most accurate values until the final answer. If you want to make things easier, if you know the answer would be 4 sig figs, I would round the numbers before to 5 to six sig figs to stay safe of missing the answer by a 0.001. Another thing you can do is use you calculator and use the ans function so it uses the exact number and carry on through the problem using the ans function.

Eliana Carney 3E
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Re: Rounding

Postby Eliana Carney 3E » Fri Oct 09, 2020 4:48 pm

You should wait to round until the last step of the problem for the most accurate answer. Personally, I keep the values stored in my calculator and use the stored values for further calculations within the problem. This saves you the time of having to retype precalculated values.

Carly_Lipschitz_3H
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Re: Rounding

Postby Carly_Lipschitz_3H » Sat Oct 10, 2020 6:16 pm

Sara_Lim_3K wrote:A friend of mine heard this rounding rule in her chemistry class (not at UCLA):

"If the digit removed is 5, the preceding number increases by 1 if it is odd and remains the same if it is even: 17.75----->17.8; 17.65----->17.6"

Neither of us had ever heard of it before, has anyone else? Is this a widely used rule or are there just certain institutions that might use it?


Hi Sara! I've never heard of that rounding rule either. I always prefer to wait until I'm done with my calculations and am at the very end to round my final answer. By keeping as many sig figs throughout my calculations as possible, I find that my answers are as accurate as possible. I'm not sure how well that rounding rule would work.

alexandralopez 3F
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Re: Rounding

Postby alexandralopez 3F » Sat Oct 10, 2020 7:17 pm

i agree with everybody else who replied. Your best bet is storing the numbers and rounding only until you have your final answer.

good luck!

Liam Bertrand 3
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Re: Rounding

Postby Liam Bertrand 3 » Sat Oct 10, 2020 7:22 pm

Thanks for the advice, I'd been rounding as you would in a math class and my answers were a bit off. Thanks!

Ralph Zhang 2L
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Re: Rounding

Postby Ralph Zhang 2L » Sat Oct 10, 2020 7:40 pm

The way I always do it is writing down all the steps first, then keep it all in the calculator until the final step, where you round to the required sig figs.

Gerardo Ortega 2F
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Re: Rounding

Postby Gerardo Ortega 2F » Sat Oct 10, 2020 7:49 pm

If the problem has multiple steps, you should leave the values you get after each step in your calculator and round at the very end to ensure that your final answer is as accurate as possible.

Sabrina Galvan 3J
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Re: Rounding

Postby Sabrina Galvan 3J » Sat Oct 10, 2020 8:21 pm

Darren1e wrote:Some elements of the periodic table have 4 sig figs as their molar mass and others have far more. When calculating the molar mass of a compound, how many sig figs should there be or number be rounded to?

For molar masses, typically the most sig figs that should be accounted for in the compound is four. However, still be sure to look for other values within the problem that have less than the equivalent of four sig figs, as they will be the determining amount of sig figs found in your final answer.

Abraham De Luna
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Re: Rounding

Postby Abraham De Luna » Sun Oct 11, 2020 5:28 pm

Normally you would want to wait until the final answer before you round.

Brandon McClelland3L
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Re: Rounding

Postby Brandon McClelland3L » Sun Oct 11, 2020 5:34 pm

Try to use the most exact numbers possible until you submit your final answer. Then, use sig figs to determine how much you have to round.

Bai Rong Lin 2K
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Re: Rounding

Postby Bai Rong Lin 2K » Sun Oct 11, 2020 9:07 pm

Are we suppose to always round to maintain the same sig figs?

Blas_Rodriguez_1B
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Re: Rounding

Postby Blas_Rodriguez_1B » Sun Oct 11, 2020 11:19 pm

you would round your final answer to avoid any mistakes as you continue to do your work and to keep the answer as precise as possible.


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