Crack the case with George Cornelius Factor in this entertaining math adventure that introduces simplified and reduced fractions with equal parts intrigue and humor. When a valuable fraction goes missing, George Cornelius Factor (a.k.a. GCF) vows to track it down. Knowing that the villainous Dr. Brok likes to disguise his ill-gotten fractions, GCF invents a Reducer--half ray gun, half calculator-- that strips away the disguise, reducing the fraction to its lowest common denominator and revealing its true form. With the Reducer in hand, George seeks out Dr. Brok in hopes of retrieving the missing fraction. Back matter includes more detail on simplifying, or reducing, fractions.