This activity has 40 math riddles that involve mental math computation with 4 numbers and 3 operations (i.e. divide the number of years in a century by the number of fingers on one hand, add the number of wheels on 5 tricycles, and multiply by 2.) These exercises are intended to strengthen students' mental math skills by reading aloud the riddle to the students and having the students compute the answer without paper, pencil, or a calculator. Included is a teacher copy that has all the riddles and the answers and 40 colorful task cards with the same riddles that can be used in centers or for students to read aloud to one another. This edition is the third of three levels. The first level is also available for purchase and has riddles that involve 2 numbers and 1 operation. The second level is a free edition and has riddles that involve 3 numbers and 2 operations. The varying levels makes differentiation easy.