I hope this is the right place for this question. I had to do a fourier series for a sawtooth wave f(t) = t from 0-1 and simulate it in excel, and put it through a low pass filter, also done in excel. I've been having problems with the filter, but that's beside the point. I have the fourier series done; once I made the spreadsheet and had a perfect sawtooth wave when I graphed my points. The problem is this: in order to get something I would consider a good sawtooth wave, you need to sum a good amount of frequencies for each point and you need A LOT of points to demonstrate its "sawtoothiness"; also I seem to have misplaced my file. Is there a faster way to do this in excel other than plugging a bunch of functions into each cell and then dragging them down 100 or so terms? I believe in my original I went somewhere near BZ 150 square (with some graphs of course). I really don't want to have to type 100~ formula's again. Some sample codes: My t values =ROW()/50 - 0.02 (C column) my fourier transform results =-SIN(2*ROW()*PI()*($C$2))/(ROW()*PI()) where row*pi is n*pi from my fourier series results (and this is dragged out a lot of columns) and I guess that's about it, but I need to go through and amend that formula around 100 times to go from C2 to C* (again, my t values), 1 for each column out a lot of terms. Is there a way to increment things via columns? I'm already using my row's for n values.