Have students pair up and "battle" each other with this random number battle.
Use a scientific calculator, graphing calculator, or a die to generate random numbers and call them out to the class. Students start on the first expression and fill in a box each time a number is called out. The objective is to obtain a larger answer than the person they are battling.
This is by far the most fun activity I have used on the day of (or near) Halloween. Students love it and they are excited to be doing math!