Help on with an SAT math problem please!

<p>Ok, I have a feeling that one is going to pop up tomorrow. It's the annoying problem like
They give you a sequence and then it asks to find like the 204th term. How do I solve these?</p>

<p>On the regular SAT, you aren't expected to memorize formulas for the nth term of an arithmetic or geometric sequence. This may not be the case for the subject tests.</p>

<p>On the SAT, they will give you the first few terms of either type of sequence, and then ask for the difference between the 200th and 210th term (for arithmetic) or the ratio of the 12th term to the 15th term (geometric). (These are just examples of course.) You should know how to do these types of questions.</p>

<p>But how do you solve those questions? I've got the same problem when it comes to sequences. I know there is a formula, but I can remember it.</p>

<p>Un = U1 + (n-1)d</p>