Corrections and Updates
Mistakes we have fixed, and how to tell us about one.
We check every formula and worked example by calculation before a page is published, and we cite our sources. Mistakes can still slip through. When a reader finds one and we confirm it, we fix the page, add a note under the “Checked” line at the end of that page, and list the correction here with its date.
Read how we write and check our pages for what “checked” means.
Corrections we have made
No corrections have been published yet. When a reader finds a mistake and we confirm it, it is fixed on the page and listed here with the date.
Report an error
Found something wrong, unclear or out of date? Tell us which page and what it should say. You do not need an account. Add your email address only if you would like a reply; we use it for that and nothing else.