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### Standard Cell Potential Significant Figures on Midterm

Posted: **Sat Feb 20, 2016 1:55 pm**

by **Ranger Saldivar 2D**

For the recent midterm on question 8 why is there three siginificant answers in the form of 1.20V when the two other cell standard cell potentials of .80V and -.40V only have 2 significant figures?

### Re: Standard Cell Potential Significant Figures on Midterm

Posted: **Sat Feb 20, 2016 3:38 pm**

by **Bryan Lau 3H**

Because for addition the rules for sig figs are different. You round with respect to the number whose digits place ends furthest to the left. For example, .80 and .40 are both to the hundredths place, so the answer upon addition will be rounded to the hundredths place.

Therefore, the answer is 1.20 and not 1.2

### Re: Standard Cell Potential Significant Figures on Midterm

Posted: **Sat Feb 20, 2016 10:32 pm**

by **BrandonV**

Because .80V and .40V is the same as 0.80V and 0.40V, which is 3 significant figures

### Re: Standard Cell Potential Significant Figures on Midterm

Posted: **Fri Feb 26, 2016 12:38 pm**

by **Bryan Lau 3H**

BrandonV wrote:Because .80V and .40V is the same as 0.80V and 0.40V, which is 3 significant figures

Actually, I don't think you should consider the sig figs like this. 0.80V and 0.40V are still 2 sig figs. Rather, you should treat the sig figs like how I mentioned in the previous comment. Rules for sig figs are different when dealing with addition/subtraction, compared to when dealing with multiplication/division.