Can you figure out easy-looking math sum in 30 seconds by remembering the special rule?

The answer to this mathematical brain teaser is NOT 40 - can YOU solve it in 30 seconds by remembering the special rule?
The New York Times

The Oura Ring 4 Can Tell You How You Slept or Predict a Cold. Is It Worth It?

We independently review everything we recommend. When you buy through our links, we may earn a commission. Learn more› By Ayanna Redwood-Crawford Ayanna Redwood-Crawford is a writer covering beauty ...
Santa Clara University

Words Matter: Illegal Immigrant, Undocumented Immigrant, or Unauthorized Immigrant?

Jonathan Kwan (@migrationethics) is the Inclusive Excellence Postdoctoral Fellow in Immigration Ethics with the Markkula Center for Applied Ethics. Views are his own. What term should we use to ...