### Sig Figs

Posted:

**Wed Oct 04, 2017 9:01 pm**I'm a little confused about sig figs. How many sig figs are in 460? and why do some questions have a number then a period after? ex. 898.

Created by Dr. Laurence Lavelle

https://lavelle.chem.ucla.edu/forum/

https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=8&t=21848

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Posted: **Wed Oct 04, 2017 9:01 pm**

I'm a little confused about sig figs. How many sig figs are in 460? and why do some questions have a number then a period after? ex. 898.

Posted: **Wed Oct 04, 2017 9:05 pm**

I believe 460 has two sig figs because the zero is just a place holder and the period after "898." is supposed to be a decimal point. I think they are mainly used to say that a zero is significant.

Posted: **Wed Oct 04, 2017 9:12 pm**

There are 2 sig figs in 460. In this case, the 4 and the 6 are significant. All nonzero numbers are significant, so in 123.45, there are five sig figs. Also, all zeros in front of a number without a decimal point in front of them are insignificant, so in 00460, there would still be just two sig figs. All zeros in between two nonzero numbers are significant, so in 4060, there are three significant figures: the 4, the first 0, and the 6. Furthermore, zeros after nonzero numbers are insignificant, so in 460000, only the 4 and the 6 are significant. However, all zeros at the end of a number that includes a decimal point ARE significant, so in 46.000, all five of the digits are significant. You will probably only see a decimal point with a whole number that ends in a zero since 460 has two sig figs but 460. would have three sig figs since the number contains a decimal.

Posted: **Wed Oct 04, 2017 9:15 pm**

The period at the end would have significance if the number ended in zeroes. For example, the number 100 has only one sig fig, while the number 100. has three sig figs because those two zeroes are now captive.

Posted: **Wed Oct 04, 2017 9:45 pm**

You can look at Dr. Lavelle's "Everything you want to know about Sig Fig" under Course Materials on his website. It is very helpful!

Posted: **Wed Oct 04, 2017 10:11 pm**

I find that a useful tip for finding the number of sig figs is to put the number into scientific notation! So for 460, it'd be 4.6 x 10^2. In scientific notation, it's a lot easier to check sig figs.

Posted: **Wed Oct 04, 2017 10:21 pm**

I get confused with sig figs when there are zeros. For example, if the number is 0.020, is there 2 or 3 sig figs?

Posted: **Wed Oct 04, 2017 10:51 pm**

Hi Michelle,

Leading zeros are not significant digits so 0.020 would only have 2 sig figs. The 2 and the 0 after it are significant digits.

Leading zeros are not significant digits so 0.020 would only have 2 sig figs. The 2 and the 0 after it are significant digits.

Posted: **Wed Oct 04, 2017 10:53 pm**

MichelleKaku1H wrote:I get confused with sig figs when there are zeros. For example, if the number is 0.020, is there 2 or 3 sig figs?

This example would only have 2 sig figs because only the trailing zeros are significant if they are after a decimal point. Any leading zeros before a non-zero number is not significant, so those first two zeros are not significant. If you want a trick, you can try to rewrite it in scientific notation (it would be 2.0 x 10^-2) and then it becomes easier to see which zeros are significant and which ones are not.

Posted: **Thu Oct 05, 2017 1:14 am**

If it was .5060 and you wrote it in scientific notation, It would be 5.060 x 10^-1 so would there be 3 or 4 sig figs?

Posted: **Thu Oct 05, 2017 12:39 pm**

There would be 4 sig figs in .5060 or 5.060 x 10^-1 because the numbers "5" and "6" sandwich the zero in between them, thus making the first zero significant.

for the last zero it is significant because any zero after the decimal point that is not a placeholder is significant. The zero is significant because it helps become more precise.

hope that helps <3

for the last zero it is significant because any zero after the decimal point that is not a placeholder is significant. The zero is significant because it helps become more precise.

hope that helps <3

Posted: **Thu Oct 05, 2017 12:40 pm**

Lauryn Jordan 3B wrote:If it was .5060 and you wrote it in scientific notation, It would be 5.060 x 10^-1 so would there be 3 or 4 sig figs?

There would be 4 sig figs in .5060 or 5.060 x 10^-1 because the numbers "5" and "6" sandwich the zero in between them, thus making the first zero significant.

for the last zero it is significant because any zero after the decimal point that is not a placeholder is significant. The zero is significant because it helps become more precise.

hope that helps <3

Posted: **Thu Oct 05, 2017 3:42 pm**

Also, when you are doing the problem, you should keep the number of sig figs the same throughout the work of the problem until you get an answer. Once you have your final answer, you may adjust it accordingly to the number of sig figs in the number specifically listed in the question.