The tethracruxifact (also called hecato-tethracross) is equal to E100(#^^##)^#100 using Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name "hecato-tethracross" is based on the prefix "hecato-" (meaning 100) and the number "tethracross".

The name "tethracruxifact" is based on the number "tethracross" and the word factor, because #^^# is the only factor of the hyper-product.

Approximations in other notations

Notation Approximation
BEAF \(\{100,100 (X \uparrow\uparrow\uparrow X*X) 2\}\)[2]
Bird's array notation ????
Fast-growing hierarchy \(f_{\zeta_0^\omega}(100)\)
Hardy hierarchy \(H_{\zeta_0^{\zeta_0^\omega}}(99)\)
Slow-growing hierarchy \(g_{\vartheta(\zeta_{\Omega2}^\omega)}(100)\)


  1. Saibian, Sbiis. 4.3.7 Extended Cascading-E Numbers Part IOne to Infinity. Retrieved 2017-01-02.
  2. Using particular notation \(\{a,b (A) 2\} = A\ \&\ a\) with prime b.
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