What are Significant Figures, Precision & Accuracy in Chemistry & Physics?

In this lesson, you will learn what significant figures are and why they are important in chemistry and physics. We will also learn what precision is and how that concept compares with accuracy. We will use the concepts of significant figures, precision, and accuracy to learn how to properly make calculation and round the result. Because of this, these concepts affect all calculations in chemistry and physics.

[TamsinJones]

You are the science teacher I wish I had had in school!

[ClumpyLemons]

As an aside: the speed at which this man draws and sheaths his dry erase markers is truly impressive.

[ArtisanTony]

10 x .5 = 5 and 10 x .05 = .5 so how are leading zeros after a decimal insignificant? Would you rather have 5 grams of cyanide or .5 grams of cyanide? One will take you out, you can survive the other :)

[bobvines]

I remember (I'm dating myself now! ;) arguing with another Engineer about significant figures when he had just learned to use a spreadsheet on one of the first PCs we had at work. (This was _way_ before Microsoft Excel!) He had learned how to cause the spreadsheet to display numbers/results to a set number of places, but had chosen to display _everything_ to two decimal places (in this example) because he wanted everything to "look good" when he printed it out for a report. However, some of his "input data" was good to only one decimal place. It took a while, but I finally got him to realize his error & accept that he simply couldn't submit a report with bogus "accuracy"/significant figures that were simply a figment of his imagination.

What Jason presents here is very important!

[frankroper]

Chemistry and physics are my favorite subjects since they are the foundations of the world we live in. I of course dont understand it all but it is fun to learn about...even better than a fiction novel!

[kidzfromthebloc]

I don't understand why the number of microseconds in a week is not exact. The second is an SI unit which means it has a standard so the microsecond by extension is an SI unit and yes with leap years we have 366 days per year instead of 365 but how does that affect your seconds? There's still 1000, 000 microseconds in 1 second and 60 seconds in a minute. Those are all just conversion factors therefore exact numbers

[shelter]

I appreciate you sir, how much full course of Maths

[ferengiprofiteer]

Thank you!
I felt sure ancient tree rings contained no significant figures for temperature.
You just proved it.

[MarkInLA]

If we're all scientists employed in a professional situation, who/why would insignificant numbers be present, to begin with ?

[robertwatson]

having worked in a retail gun shop for five years I can say the average firearm owner has difficulty understanding any of this. Most customers are influenced by myths and misconceptions about firearms in general. The worst one is the misconception that projectiles rise after leaving the barrel. I used to draw diagrams for the customers in an effort to show them what actually happens. ALL of them rejected the information. Each would quote some article they read which they believed to be correct and this contradicted what I showed them---so they rejected my information. Ignorance abounds and the public desperately clings to it.

[주명화-wc]

Strange ideas of significant figure for today lesson, to take 3000 for example to show how wierd this principle is acting in real situation. We figure out which numbers are significant and which are not. It says that 3 trailing zeros in 3000 are not significant for the zeros following after the exact number 3 are not considered to be so. But in reality the zeros after 3 have a certain meaning in that number obviously whether in its quantity or quality or whatsoever in comparison with just single number of 3. But on the contrary, how about the trailing zeros of any number in digits after decimal? Obviously we would ignore the amount of meaning in that position just because they are not so significant to consider in real situations. But also we will put some values in the leading zeros before or after decimal, because they can be converted into the form of percentages. And percentages have a significant meaning we shouldn't ignore. So the leading zeros should be considered to have real values in real situations while the trailing zeros have little or null meaning in reality. Cause there's no significant difference between 3 and 3.0 and 3.00. They are all equal to 3. So this is rather strange lesson full of distorted ideas about real significance of numbers in real values.

[hemarajue]

I think 020 has one significant digit and placing decimal point at the end doesn't make a difference.

[romanporsche]

So it is not possible for a thing to have high accuracy and low precision.

[ArtisanTony]

The truth may also just be a goal you have set to reach because we do not always know the truth :)

[wouldbfarmer]

I ain't buying the trailing 0s significance explanation you give....