I would not phrase it this way. Which reminds me of newspapers reporting that Fermat's Last Theorem is essentially the Pythagorean theorem (solely because the same expression arises. Here is the Wikipedia article, in which Dedekind eta is defined: https://en.wikipedia.org/wiki/Dedekind_eta_function namely: eta(t) = exp(2pi*i*t/24) Product_{1<=k<oo} (1 - exp(2pi*i*t)^k) which is of course vaguely related to Product_{1<=k<oo} (1 - (1/10)^k) but with major essential differences. Dan ----- Note that product(n>=1, 1-10^{-n}) is essentially Dedekind's eta function and Euler's pentagonal number theorem (to name just one) may be helpful with spotting patterns in the expansion. -----