This neat little video explains the importance of significant figures, rounding, accuracy and precision. Find out why adding a single drop of water (of about 0.05 ml) to a cup of coffee that is about 200 ml should never be written as 200.05 ml
It’s all about the errors and the significance of the digits in each measurement. The video also provides a useful introduction to scientific notation and underpins the origins of the Sig Figs website you are reading now, because so many times the news and other media don’t seem to understand significant digits and get it wrong again and again. Just check out the archives to see exactly what I mean!
By the way, there’s an online significant figures calculator here It works very well and has a nice example to help you. As it’s fairly new, please let me know how you get on with it in the comments below.