´╗┐David Garlock is a´╗┐ life-long lover of mathematics and brainteasers. His day job is as a tax advisor with Ernst & Young LLP in Washington, DC, and he also teaches a course in Number Theory at Georgetown Day School. David has an A.B. in Mathematics from Harvard College and a J.D. from Harvard Law School. He lives in Chevy Chase, Maryland with his wife Barbara and has three adult daughters. David is the principal author of a major tax treatise and numerous articles in professional journals.