Findum.net is a great multiplayer game suitable for all ages that is not only fun and lighthearted, but also has some educational value.
There are many numbers randomly written on a whiteboard. The goal of the game is very simple: you need to be find and circle the number shown at the top. The first player who marks the number gets a point. When all the numbers are marked, the player with the most points wins.
If you like number games and well meaning competition, you will probably enjoy Findum.net.