# significant figures

### Accuracy, precision, and significance: The misery of cholera

We’re bombarded with numbers every day. But seeing a number and understanding it are two different things. Far too often, the true “significance” of a figure is hidden, unknown, or misjudged. I will be returning to that theme often in these blog posts in the context of water, climate change, energy, and more. In particular, there is an important distinction between accuracy and precision. Here is one example – reported cases of cholera worldwide. Cholera is perhaps the most widespread and serious water-related disease, directly associated with the failure to provide safe drinking water and…

### Significant figures what are they for and what do they have to do with uncertainty?

Suppose I am working on a problem and I wish to calculate the density of something. I measure the mass to be *m* = 24.5 grams and the volume is *V* = 10 cm3. In this case the density would be: ![Sigfig 1](http://scienceblogs.com/dotphysics/wp-content/uploads/2008/09/sigfig-1…) ALERT! ALERT! ALERT! This is not a test!!!! Something is drastically wrong! Clearly I messed up. How can I have the mass measured to **3** significant figures, the volume measured to **1** significant figure, but the density calculated to **3** significant figures? Isn't this a violation of some fundamental…