<p>This is something I'm fuzzy about. I've seen a few questions in my book/on AP free response that ask you to calculate the nth partial sum. However, sometimes a series starts at n = 0. Is the 4th partial sum the first four terms, or is it all the terms up to n=4 (which would be 5 terms, assuming n starts at 0).</p>
<p>It's not always clear. Thanks for any help.</p>
<p>Starts at n=0. Goes up to n=4. So 5 terms.</p>
<p>I agree with hotinpursuit. However, I don’t think my teacher has ever mentioned a question asking for a nth partial sum or ever seeing a question asking for one in the packets my teacher gives. I doubt such a question would appear on this year’s AP test, but you never know.</p>
<p>^Yeah, you never know lol. I would hate to get one of these questions and calculate the wrong sum for the first part, then miss the whole question.</p>
<p>hotinpursuit: Yeah, I know it’s five terms. But for some reason the notation differs sometimes. The fifth partial sum will be the first five terms, but then they write the actual summation as (S-subscript-4 = n(0)+n(1)+…n(4).)</p>
<p>Which means that S-subscript-4 supposedly denotes that it sums up to n=4, but it’s really 5 terms because it includes n=0.</p>
<p>Something that I suggest doing is this:</p>
<p>Make little numbers starting from your bottom value up to your top. Then, put lines above each little number and write the value of the term on the line. That way, you know how many terms to find and the n-value of each term, so you don’t accidentally start from the wrong n or go up to the wrong n.</p>