Which comes next in the pattern 2, 6, 18, 54, _?

In order to answer this question, you first need to know what the sequence of the numbers is. What are the common things about the numbers? You can see that for every number; the value is tripled.

From 2, the next number became six. If you would multiply 2 by 3, you will get 6. Then the next number after 6 is 18. If you would multiply 6 by 3, you will get 18. This means that the last number, which is 54, should also be tripled. 54 multiplied by 3 is 162, so this will be the next number in the sequence.

Sequencing is one of the things that people usually do in order to test their IQ. The faster that they are able to see the needed sequence, the faster their IQ is supposed to be.

The differences between each of the numbers reveals that a tripling of the first figure results in the one following. Therefore, two multiplied by three equals six. Then multiplying six by three makes eighteen, and so on.

Once a child has the experience of one of these types of problem, it is easy for him to solve any new ones as they are usually a function of the four rules applied forwards or backwards.

It is only an intelligence test when the child first comes across an example and works out what is happening for himself. After that, practice on such problems leads to rapid success, not just IQ.