Need a fun way to practice using input/output tables? This is a set of 2 self-checking worksheets - each with a riddle to solve. Students will find the rule for input/output tables, then use the rules to find missing sums, differences, products, or quotients. Then they will match their work to answer a riddle at the bottom of each worksheet - math is so much fun! Use as an end of unit quiz, independent practice, or allow students to race to find the answer the riddle! Don't want to pri