| Author | Significant Figures |
|---|
how many sigfigs would i have if the problem is:
1/27.7
the answer is 0.0361 but how do i write it down,
3.6e-2 or
4e-2
or what? |
1/27.7 = .03610108303249097(47292418772563176895306859205776173285198555956678\
7003610108303249097)
The (X) part means the X keeps on repeating forever.
That means your number 1/27.7 has an infinity of significant digits, since the digital expression of your number requires an infinity of digits to express precisely
For the record: The significant figures of a number are those digits that carry meaning contributing to its precision.
Probably you are asking the wrong question? Is this in the context of a floating point number system with a certain length of the mantissa? |
| what i mean is, what is the answer to 1/27.7? :) in scientific notation and sigfigs |
| It depends on how many significant digits you want to use. |
you can't pick how many sigfigs to use... there are rules
http://www.webassign.net/sigfigs.html
but im not sure about 1/27.7 what the answer will be |
The number of significant figures (digits) depends on the computational floating point number system you are using.
So when you ask what is the answer to 1/27.7, you should specify which floating point number system you are using, because that one determines how many significant figures you are considering.
From the link you provided, it seems you are asking this in the context of some tool called WebAssign. I'm not familiar with this one, so I can be of no further help...
For a general view about significant figures, you may also check this: http://en.wikipedia.org/wiki/Significant_figures |
Example: When multiplying 22.37 cm x 3.10 cm x 85.75 cm = 5946.50525 cm3
We look to the original problem and check the number of significant digits in each of the original measurements:
22.37 shows 4 significant digits.
3.10 shows 3 significant digits.
85.75 shows 4 significant digits.
Our answer can only show 3 significant digits because that is the least number of significant digits in the original problem.
5946.50525 shows 9 significant digits, we must round to the tens place in order to show only 3 significant digits. Our final answer becomes 5950 cm3. |
| Web Assign is just a website where my chemistry teacher posts up Homework. |
sigfig rule for Multiplying/dividing
RULE: When multiplying or dividing, your answer may only show as many significant digits as the multiplied or divided measurement showing the least number of significant digits.
so im guessing the answer will be:
4e-2 right? |
3.10 shows 3 significant digits.
This is not correct! 3.10 has only 2 significant figure. The last 0 is not a significant digit.
It seems your chemistry professor uses some different convention about significant figures. This is not a standard definition.
Also 5950 has 4 significant digits. All digits before the . are significant.
For the standard definition of a significant figure, please check this: http://en.wikipedia.org/wiki/Significant_figures
It looks to me like your question is tied up to the definition/convention/understanding that your professor uses in class. |
This is not correct! 3.10 has only 2 significant figure. The last 0 is not a significant digit.
Also 5950 has 4 significant digits. All digits before the . are significant.
no u are not correct.
3.10 has 3 significant figures, because it is not a placeholder. it shows how much of the number we know. for example:
the number is 3.1058693725.... we know for sure that the first three numbers are 3.10 but we don't know the rest, 3.10 is significant.
5950 has 3 sigfigs because the last 0 is a placeholder. if it was 5950. then it would be 4 sigfigs because of the decimal point 5950"." |
3.10 = 3.1
so the last 0 is not significant. you can just not write it and the precision of the number is the same. |
no, if you write down 3.10 is more precise than 3.1 because just like i said, if the real number is
3.1058693725....
and we are looking for the next digit, we definitely know that it is 0 if we have the number 3.10. but if it's 3.1, then you have to find what the next digit is... |
To break up the fight....
3.10 = 3.1 correct
but for significant digits it is incorrect.
22.37 shows 4 significant digits.
3.10 shows 3 significant digits.
85.75 shows 4 significant digits.
Wrong; it is 2 significant digits for all.
5946.50525
Answer should be 5946.50
This is because the original numbers are only as accurate as up to the 2nd decimal place. |
1 has one sig fig
27.7 has 3 sig figs
you must use the amount of sig figs in the answer as the least in the problem
so the answer should only have 1 sig fig
3x10e-2 |
I agree with Diversecity, in terms of number of sig figs. You can only be sure of your answer by the same level you are sure of your original data to find teh answer, hence, you quote your answer to the lowest number of sig figs = 1 in this case.
However, as a chemistry teacher in exams it comes slightly differently, and this rule is usually apllied slightly differently. In exam paper mark schemes it is always quoted as 3 or 4 sig figs, and as a general rule with chemical calculations it is wise to quote to this level, even if on some occassions the data doesn't directly support this.
Finally, it depends on what you intend to do with the number, because if it is an intermediate step in a question you shouldn't round at all, as you only do this at the end. |
3x10e-2
3.6 round up to 4 so i guess then the answer is 4e-2 |
and one more question:
What amount (moles) is represented by this sample?
2.82*10^21 molecules of ethanol, C2H5OH |
one mole is equal to Avogadros constand of 6.023 *10^23
Therefore divide the number of molecules, by this number to get your total number of moles.
I cannot be bothered to get a calculator but it will be around 0.01 moles |
Are you sure it's not a trick question?
1/27.7 can also be expressed as 27.7 to power -1. That would make it 3 significant figures.
So the answer would be 0.0361
Have Fun
Grunge |
