How to limit character of Text box?

I need a validation on one of my fields. The user needs to enter a number between 0 and 8. Please advise how I do this.

I thought that is the number of characters, not the number itself. They can only enter the following numbers:

1

2

3

4

5

6

7

8

That can be accomplished using a "Number" field and setting the minimum to 1 and the maximum to 8:

Here is a quick test form to show you how it works:

http://form.jotformpro.com/form/51386599914976

If you have any further questions, let us know and we will be happy to help.