Deciding whether a given language is regular [duplicate]

I am struggling with a homework assignment. This next question seems to be pretty easy, once I get what I feel like I'm missing now. Anyway, here goes:

Decide if the following language is regular or not and prove your claim.

$$L=\{a^{i_{1}}ba^{i_{2}}ba^{i_{3}}ba^{i_{4}}ba^{i_{5}}ba^{i_{6}}ba^{i_{7}}b|i_{1}>i_{2}>i_{3}>i_{4}>i_{5}>i_{6}>i_{7};i_{1}<100\}$$

So, how do I go about doing so? Is there a thumb rule that might help? I was trying to use the pumping lemma to prove that it is not regular, but couldn't do it. I'm not even sure it really is not regular.

Any suggestions?

marked as duplicate by Paresh, vonbrand, Raphael♦Mar 17 '13 at 18:08

Hint: Consider how many words are in $L$. The answer will then be immediate.