Mathematicians and hobbyists have had a half-century of fun exploring the some 43 billion billion permutations of Erno ...

Apple, penny, table. I had my dad do something like this ... Two weeks later, he called to tell me he had printed out my ...

The afternoon train was late into the town of Lexington. Mary \u2014 stout, graying, and as taciturn as a desert tortoise \u2014 waited on the train platform, getting antsy.

National Geographic’s photography community is now on Instagram at @NatGeoYourShot. Please follow us there for the latest photos from the community and tag your photos #YourShotPhotographer for ...