In the third century BCE, Apollonius of Perga asked how many circles one could draw that would touch three given circles at exactly one point each. It would take 1,800 years to prove the answer: eight ...

Want to help your seventh-grader master math? Here are some of the skills your child will be learning in the classroom in seventh grade. At a “25% Off” sale, Marissa buys a skirt for $40.50. What was ...