The tethracross-carta-tethracubor is equal to E100#^^###100#^^##100 using Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number is based on the numbers "tethracross" and "tethracubor".

Approximations in other notations

Notation Approximation
BEAF \(\{100,101(X \uparrow\uparrow\uparrow X) 2 (X \uparrow\uparrow\uparrow\uparrow X) 2\}\)[2] (weak bound)

\(\{100,101(X \uparrow\uparrow X^{2}) 2 (X \uparrow\uparrow X^{3}) 2\}\) (strong bound)

Bird's array notation ???
Fast-growing hierarchy \(f_{{\varphi(3,0)}+\zeta_0}(99)\)
Hardy hierarchy \(H_{{\varphi(3,0)} \zeta_0}(99)\)
Slow-growing hierarchy \(g_{\vartheta(\varphi(3,{\Omega 2})+(\zeta_{\Omega+1}))}(99)\)


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