## diference in sig figs

danielruiz1G
Posts: 62
Joined: Fri Apr 06, 2018 11:04 am

### diference in sig figs

What is the difference when multiplying, dividing, adding, subtracting when accounting for significant figures?

Chem_Mod
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### Re: diference in sig figs

The rules for sig fig is different. Multiplication and division is simple in that you keep the same number of digits as the smallest number of sig figs in your mathematical operation. For addition and subtraction, you must keep the sig fig until the digit of the least accuracy.

EllenRenskoff-1C
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Joined: Fri Apr 06, 2018 11:04 am

### Re: diference in sig figs

Does that essentially mean that for multiplication and division we are basing the answer on the least number of sig figs present whereas for addition and subtraction we are basing it on the the least number of decimal places present?

204917020
Posts: 31
Joined: Fri Apr 06, 2018 11:05 am

### Re: diference in sig figs

EllenRenskoff-1C wrote:Does that essentially mean that for multiplication and division we are basing the answer on the least number of sig figs present whereas for addition and subtraction we are basing it on the the least number of decimal places present?

Yes, for multiplication and division, your answer will have the same number of significant figures as the number with the least amount of sig figs. For subtraction and addition, since it is based on the number with the least accuracy, your answer will have the same number of digits after the decimal as the number with the least amount of digits after the decimal.

Alexis Bravo 1D
Posts: 30
Joined: Tue Nov 14, 2017 3:01 am

### Re: diference in sig figs

Could you please give an example of how it would work for sig figs with addition/subtraction? Would that mean that adding something like 3.045+7.26 would result in an answer with only two figures after the decimal?

Chem_Mod
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### Re: diference in sig figs

3.045 + 7.26 = 10.305

Since the least accurate digit is the 1/100th place, you round to that digit. The digit to the right of 1/100th place is a 5. (this actually gives a headache because when it is exactly 5, you need to make sure your 1/100th digit rounds to an even number) So your final answer is 10.30

Slightly different examples:
3.045 + 7.36 = 10.315 = 10.32

3.046 + 7.26 = 10.306 = 10.31