Animals know a lot more about numbers than you might think. Guppies can tell large numbers from small ones, hyenas can count, and chimpanzees can use Arabic numerals! Readers will get to know these extraordinary animals and more--and how scientists study their number sense. Each chapter wraps up with an interview with a researcher and a hands-on activity that give readers the chance to challenge their own math skills. Illustrations brimming with personality, along with colorful photos, sidebars, and splashy facts, make for an entertaining delve into these fascinating studies in this second book in the Extraordinary Animals series. A bibliography as well as an "Add to Your Knowledge" section at the back encourage more discovery.