This is a game for a whole class or group.

You need a 100-Square or a list of at least 20 numbers or mathematical expressions. These can be large for all to see or players can have their own copy.

A rule is chosen by the teacher (or pupil acting as 'leader'). This might be "even", "a multiple of 5", "square number", "prime" etc.


The leader says, for example, "I like 36, but I don't like 23."
(The leader 'likes' those examples that follow the rule, and 'does not like' examples that do not follow it.)

Class members then ask such questions as "Do you like 25?"and "Do you like 18?"

The leader answers, for example, "I don't like 25," or "I do like 18" according to the chosen rule.
When a player is quite certain that they know the rule then they ask, for example, "Is the rule all multiples of 9?"