Sig Figs- Addition and Subtraction  [ENDORSED]

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404975170
Posts: 68
Joined: Thu Jul 27, 2017 3:00 am

Sig Figs- Addition and Subtraction

Postby 404975170 » Thu Oct 05, 2017 8:18 pm

In Appendix 1C there is a rule that says to "make sure that the number of decimal places in the result is the same as the smallest number of decimal places in the data." How does this work if one of the numbers you are adding does not have decimal places? For example: 12+ 0.123=

alyssawhite1L
Posts: 20
Joined: Fri Sep 29, 2017 7:05 am

Re: Sig Figs- Addition and Subtraction

Postby alyssawhite1L » Thu Oct 05, 2017 8:38 pm

I believe that that section is simply proposing a trick to facilitate counting sig figs when you are only dealing with numbers with decimal places, ex. .10 + .024 = .12. However when you are adding a whole number to a decimal, 12 + .123, you can use this rule, with your answer thus being rounded to the 1s place because that is the least amount of decimals (0 decimals to be exact) and your answer would be 12.

OR you can simply get your answer of 12.123 and round it to the least number of sig figs of your reactants. (12 having only 2 sig figs would be your smallest). SO, your answer would also be 12 - just found without the trick.

Payton Schwesinger 1J
Posts: 45
Joined: Fri Sep 29, 2017 7:04 am

Re: Sig Figs- Addition and Subtraction

Postby Payton Schwesinger 1J » Thu Oct 05, 2017 9:55 pm

Okay thank you Miranda- so then you only have to look at the number of significant figures and just do the one with the least amount? You don't even have to really worry about decimal places?

lauren chung 2f
Posts: 50
Joined: Fri Sep 29, 2017 7:03 am

Re: Sig Figs- Addition and Subtraction

Postby lauren chung 2f » Thu Oct 05, 2017 11:59 pm

You pay attention to the number with the fewest decimal places when adding and subtracting. So if you were doing 10.026 + 0.4, your answer would be 10.4 since 0.4 has one decimal place.

Tylor McGrew 1J
Posts: 20
Joined: Fri Sep 29, 2017 7:03 am

Re: Sig Figs- Addition and Subtraction  [ENDORSED]

Postby Tylor McGrew 1J » Tue Oct 10, 2017 6:45 pm

When adding and subtracting with sig figs, your final answer must be in the least amount of sig figs. For instance, if it is 9.9 -4.442, the answer would be 5.5 because 9.9 has the least amount of sig figs.


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