Chemistry

How does Significant Figures work?

If i had a number: 1,007,000 is that with 4 sig figs or 7 sig figs?

I checked 5 different resources and gotten conflicting answers.

Help!


The answer will depend on what's being measured and how it's being measured.
If that number were the amount of shares of common stock of some public company that were traded today then it could be 7 significant figures. On the other hand, if it were the number of miles some object might be from the earth then there might be only 4 significant figures. If it's some kind of measurement then most likely it has only 4 sig. figures. If it's something that can be counted, and the process is extremely accurate and verifiable, then there could be more than four signif. figures.
So the short answer is...it depends.


It is hard to tell. If there was a period at the end, such as 1,007,000. then the answer is 7 sig figures. But with no period, we don't know if the zeros are sig or not. GENERALLY, I think the rule is not to count them if there is no period. In such practice, the number would be written as 1.007E+6. Then there would be no confusion and we would count 1, 0, 0, and 7 as sig figures.


The reason you get conflicting answers is this:
The notation for significant zeros is changing. The IBM keyboard is largely to blame. Years ago, trailing significant zeros could be labeled with an overscore (a line above the number) to indicate it was significant. We cant make overscores on the IBM keyboard. So panic has ensued.
Years ago, if your number had a significant zeros, the least significant zero had an overscore (I can type it with an underscore 1,007,000, (now the number has six significant digits), but no overscore. For awhile, bold was used to indicated the least significant zero (1,007,000, but that faded quickly. So now there is no method except shifting to scientific notation (decimals to the right of numbers and decimals are significant, ie 1.00700 is seven sig digits), or being told initially.
This above applies to measurements: as Roger pointed out, counting numbers, or defined numbers,(100years in a century) are infinitely precise. If 1007000 had been counted, it does not have seven significant digits, it has infinite significant digits..It cannot determine the precision of your final outcome. This confusion based on the disruption of typesetting by the IBM keyboard in computers in the last 20 years is probably the reason you got five different answers. The most common rules widely adhered to are here:

(Broken Link Removed)

There are only three rules cited there.

I remember just 17 years ago, texts listed as many as seven rules.

For Further Reading


Thanks for this refresher Bob. It's been awhile since I looked at signif. figs. I wasn't aware that the short-comings of the keyboard were partly to blame for the confusion here. I do remember using the bar, but I couldn't remember what the rules were for it. I think some sets of rules also tell how to make calculations with measurements and determine sig. figs., that might account for the different rule counts.
In any case -if you read this Summer- always look at what your text states and know what the instructor expects. You should be alright if you do that.

  1. 👍 0
  2. 👎 0
  3. 👁 129
asked by Summer

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics Sig Figs

    When you are multiplying two numbers, how do you determine the number of significant figures? You go with the lowest sig figs in your problem. so suppose you multiply 2.34 and 8.9574, in your product you should have 3 sig figs as

    asked by Meleas on August 27, 2005
  2. Physics

    Talking about significant figures, my Physics textbook lists 5 rules for determining significant figures. 1) All nonzero digits are significant. 2) Zeros to the right of nonzero digits in a number containing a decimal point are

    asked by Autumn on August 21, 2012
  3. math

    I always thought I understood significant figures...until I attempted to tutor someone. Some of the rules seem counterintuitive. For instance... 10.070 why is it 5 sig fig's? the "0" on the right is useless. without it the # holds

    asked by Charles on January 30, 2008
  4. Math

    Rounding to significant figures 99.98 to 3 significant figures Can it apply to this number as if I round to 100 this is one significant figure or we keep it as 99.9. Please clarify And same number to 2 sig figure Will it be 100?

    asked by NJay on October 6, 2017
  5. Physics Mathematics

    do we have to have the same amount of significant numbers in the values we got by convertion? No. Your conversion factors may have some lack of precision. Examples 60sec=1min infinitely precise, a definition. 1.6km= 1mile two sig

    asked by Katrina on September 15, 2006
  6. Chemistry

    What should be the number of significant figures in the following calculation? It's an error calculation which is absolute value (True value - experimental value) / true value * 100 so it would be: absolute value [-601.7 - (-587)]

    asked by James on April 30, 2013
  7. Science

    I'm a little confused when it comes to significant figures. Where it doesn't make sense to me is when zeros come before and after a number. For example: My book states that zeros that come before a digit are NEVER significant. Now

    asked by Anonymous on December 9, 2009
  8. Chemistry

    I have a Chemistry question which should be very simple but I do not know what significant figures are. Assuming the following numbers are measurements and using the rules for significant figures, determine the answer for the

    asked by Pablo on January 10, 2013
  9. Science (Chemistry!)

    I just do not understand ANYTHING about multiplying/dividing/adding/subtracting significant figures! For example, the problem is: Solve the following to the correct number of significant figures: (5.039)(0.0074) What am I supposed

    asked by Hayley on August 31, 2006
  10. chemistry

    1. the diameter of a carbon atom is 0.000 000 000 000 154 m. what is the number expressed in the scientific notation? a) 1.54x10^12m b) 1.54x10^-12m c) 1.54x10^10 d) 1.54x10^-10 2. what is the result of multiplying 2.5x10^10 by

    asked by david on August 30, 2018

More Similar Questions