## Significant Figures

Kelsey Ash 1D
Posts: 50
Joined: Wed Sep 18, 2019 12:16 am

### Significant Figures

What are the rules for significant figures again? It's been a while since I've done this and I cannot remember how to determine the correct number of significant figures for a problem/how it would be written.

JOtomo1F
Posts: 66
Joined: Sat Aug 24, 2019 12:16 am

### Re: Significant Figures

Here are a couple rules I found online:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.

JOtomo1F
Posts: 66
Joined: Sat Aug 24, 2019 12:16 am

### Re: Significant Figures

I also read from the textbook
"When reporting the results of multiplication and division, identify the number of digits in the least precise value and retain that number of digits in the answer."
as well as

"When reporting the results of addition or subtraction, identify the quantity with the least number of digits following the decimal point and retain that number of digits in the answer."

Sarah Zhari 1D
Posts: 103
Joined: Sat Sep 14, 2019 12:16 am

### Re: Significant Figures

Generally, if a question is asking for you to add or subtract, you round your answer based on the value in your working with the least number of decimal places. For example, 33.567+2.1 = 35.7. For multiplication and division questions, you round off your answer based on the value in your working with the least number of significant figures.

505106414
Posts: 55
Joined: Wed Sep 18, 2019 12:17 am

### Re: Significant Figures

JOtomo1F wrote:Here are a couple rules I found online:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.

My question: When you say 'any zeros between two significant digits are significant', do the two significant digits need to be on the same side of the decimal point?

melinak1
Posts: 25
Joined: Tue Sep 24, 2019 12:17 am

### Re: Significant Figures

505106414 wrote:
JOtomo1F wrote:Here are a couple rules I found online:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.

what are trailing zeros in the decimal portion?

JOtomo1F
Posts: 66
Joined: Sat Aug 24, 2019 12:16 am

### Re: Significant Figures

505106414 wrote:
JOtomo1F wrote:Here are a couple rules I found online:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.

My question: When you say 'any zeros between two significant digits are significant', do the two significant digits need to be on the same side of the decimal point?

No I believe that they don't have to be on the same side of the decimal but I am not 100 percent sure of that.

JOtomo1F
Posts: 66
Joined: Sat Aug 24, 2019 12:16 am

### Re: Significant Figures

melinak1 wrote:
505106414 wrote:
JOtomo1F wrote:Here are a couple rules I found online:
Non-zero digits are always significant.
Any zeros between two significant digits are significant.
A final zero or trailing zeros in the decimal portion ONLY are significant.

what are trailing zeros in the decimal portion?

Here is an example of trailing zeros " 175.00" and that number contains five significant figures.

EmilyJoo_1G
Posts: 50
Joined: Thu Jul 25, 2019 12:16 am

### Re: Significant Figures

Sarah Zhari 1C wrote:Generally, if a question is asking for you to add or subtract, you round your answer based on the value in your working with the least number of decimal places. For example, 33.567+2.1 = 35.7. For multiplication and division questions, you round off your answer based on the value in your working with the least number of significant figures.

Hi! I'm not sure I understand what you meant. 2.1 is the value with the least number of decimal places right? So how do you get 35.7 as your answer with 3 significant figures if 2.1 only has 2 significant figures?
Or does that just mean the number of decimal places in your answer should equal the smallest number of decimal places in the question? Thanks

Posts: 102
Joined: Wed Sep 18, 2019 12:18 am

### Re: Significant Figures

Yes, your last question was correct. For example, if you were adding 3.5 and 2.11, you'd get 5.61; however, in order for the answer to be rounded to the correct number of significant figures, you'd have to make your final answer 5.6.

This is because the final answer must take the same amount of numbers behind the decimal point as the number with the least.

That was a little wordy, but to put it into perspective: 3.5 has one number behind decimal point, while 2.11 has two. Therefore, the final answer would have one number behind the decimal point, because one is less than two.

Hope this helps.

melinak1
Posts: 25
Joined: Tue Sep 24, 2019 12:17 am

### Re: Significant Figures

JOtomo1F wrote:
melinak1 wrote:
505106414 wrote:

what are trailing zeros in the decimal portion?

Here is an example of trailing zeros " 175.00" and that number contains five significant figures.

thank you so much!!