The Eddington number is \(N_ ext{Edd} = 136 \cdot 2^{256} \approx 1.575 imes 10^{79}\), which Arthur Eddington asserted to be the exact number of protons in the observable universe. 136 is the reciprocal of the fine structure constant, or at least the best available estimation at the time. It is now known to be about \(1/137.035999074\); Eddington's original value, if not his whole argument, is incorrect. Its full decimal expansion is 15747724136275002577605653961181555468044717914527116709366231425076185631031296