Mark Zegarelli is the author of SAT Math For Dummies, Basic Math & Pre-Algebra For Dummies, and nine other books in the For Dummies series. He holds degrees in both English and math from Rutgers University. Most recently, he provides online lessons for kids as young as four years old, showing them easy ways to understand -- and enjoy! -- square numbers and square roots, factors, prime numbers, fractions, and even basic algebra concepts.