CMB-slow, or How to Estimate Cosmological Parameters by Hand

I derive analytically the spectrum of the CMB fluctuations. The final result for Cl is presented in terms of elementary functions with an explicit dependence on the basic cosmological parameters. This result is in a rather good agreement with CMBFAST for a wide range of parameters around concordance model. This allows us to understand the physical reasons for dependence of the particular features of the CMB spectrum on the basic cosmological parameters and to estimate the possible accuracy of their determination. I also analyse the degeneracy of the spectrum with respect to certain combinations of the cosmological parameters.