You’re at the checkout screen after an online shopping spree, ready to enter your credit card number. You type it in and instantly see a red error message ...

Prime numbers are tricky things. We learn in school that they’re numbers with no factors other than 1 and themselves, and that mathematicians have known for thousands of years that an infinite number ...

Mathematicians love a good puzzle. Even something as abstract as multiplying matrices (two-dimensional tables of numbers) can feel like a game when you try to find the most efficient way to do it.