The Eddington number is \(N_\text{Edd} = 136 \cdot 2^{256} \approx 1.575 \times 10^{79}\), which Arthur Eddington asserted to be the exact number of protons in the observable universe.[1] 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



Notation Lower bound Upper bound
Scientific notation \(1.574\times10^{79}\) \(1.575\times10^{79}\)
Arrow notation \(183\uparrow35\) \(3\uparrow166\)
Steinhaus-Moser Notation 47[3] 48[3]
Copy notation 1[80] 2[80]
Taro's multivariable Ackermann function A(3,260) A(3,261)
Pound-Star Notation #*(7,3,8,3,5,3,1)*7 #*(5,10,5,3,2)*12
BEAF {183,35} {3,166}
Hyper-E notation 136E[2]3#3
Bashicu matrix system (0)(0)(0)(0)[89089] (0)(0)(0)(0)[89090]
Hyperfactorial array notation 58! 59!
Fast-growing hierarchy \(f_2(255)\) \(f_2(256)\)
Hardy hierarchy \(H_{\omega^2}(255)\) \(H_{\omega^2}(256)\)
Slow-growing hierarchy \(g_{\omega^{\omega^32+3}2+\omega^{\omega^32+1}2}(4)\)


See also

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