Fast Fourier transform (FFT) algorithms are able to calculate the discrete Fourier transform (DFT) in only $O(N\log N)$ asymptotical time. Since there is roughly $N\log N$ operations for computing $N$ frequencies, computing a single frequency takes basicly $\frac{N\log N}{N} = \log N$ operations.
Now, is it really possible to calculate just a single frequency with $\log N$ operations? Or is the speed-up of FFT somehow "hidden" into a bigger structure?