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The tethrahexon is equal to E100#^^#^#6 = E100#^^######100 in Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number is based on the number tethrathoth and the root "ecton" from "polyecton". Polyecton is the name for a 7-dimensional figure and 7-D figures are constructed from multiple 6-D figures (hence the "poly"), so a "ecton" can be considered a 6-dimensional figure.

Approximations in other notations

Notation Approximation
BEAF \(X \uparrow^7 101\ \&\ 100\)
Bird's array notation \(\{100,7 [1 [2 \neg 2] 2] 2\}\)
Hyperfactorial array notation \(100![1] w/9\)
Fast-growing hierarchy \(f_{\varphi(6,0)}(99)\)
Hardy hierarchy \(H_{\varphi(6,0)}(100)\)
Slow-growing hierarchy \(g_{\vartheta(\varphi(6,\Omega+1))}(100)\)


  1. Saibian, Sbiis. 4.3.3 - Forging Extended Cascading-E Numbers Part I. Retrieved May 2, 2014.