A turn based game.
For 2 or more players.
If you have achieved a level of cooperation between the children then you can get the students to talk about the moves, which they will. Direct arguments into constructive conversations about valid turns.
Scaffolding : let children use a calculator if they are still learning their multiplication tables or other reason that you as a professional deem valid.
Depending upon how advanced your students are, the more advanced they are the younger they can be.
Helpful in getting students to learn that a number is both its own largest factor and smallest multiple.