How a centuries-old math puzzle helped us see inside the human brain. By Steven Strogatz Photo illustrations by Jens Mortensen Each installment of “Math, Revealed” starts with an object ...

While the math makes sense, Petrini has bigger reasons for staying: she’s emotionally tied to the lot, the community and the people within it. Altadena is a safe haven for her.

How Much of Our Math Series Did You Retain? Try This Quiz. Test your knowledge of taxicab geometry, triangular numbers, the golden ratio and more.