Take a few pieces of paper and write a random number on each of the paper. Of course, don't forget the numbers, or write them down somewhere but don't let the students see! Also, take 4 pieces of paper and write each of the Math operation on them(+,-,/,*).
Now, hide the numbers across the classroom or spread them around a table face down. Tell the students to find/take 2 numbers and also an operation.
And now they should multiply or subtract or whatever they pulled out those 2 numbers and get a point if it's correct.