May 5 of the Mystery Year was when Mexico, in the Battle of Puebla, defeated the invading French army. Cinco de Mayo commemorates that victory. The math clues provide mixed review and test prep as middle school students find digits of the Mystery Year. The clues involve evaluating expressions, remainders in division, and converting a number in baseĀ 5 to base 10. Your ZIP download includes PDFs:A ready-to-print Student Page along with annotated Answer Key. A digital version with expanding form f