This activity is similar to my "Eliminate It, Revise It" that uses vocabulary words, but this "Eliminate It, Revise It" uses numbers.
Place four numbers at the top, one of which doesn't belong with the others. An example may be "231, 453, 37 and 1,630". The number that doesn't belong is 453 because it does not have a 3 in the tens place. (HOWEVER, students will chose numbers and justify their thinking in ways you haven't planned for, which promotes great math discussions!) Students then choose a number that does belong, titles the group and justifies their thinking.
This is a great review for prime/composite, even/odd, multiples, etc.
Enjoy! Meagan Erwin