The tethrahepton is equal to E100#^^#^#7 = 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 "zetton" from "polyzetton". Polyzetton is the name for a 8-dimensional figure and 8-D figures are constructed from multiple 7-D figures (hence the "poly"), so a "zetton" can be considered a 7-dimensional figure.

Approximations in other notations

Notation Approximation
BEAF \(X \uparrow^8 101\ \&\ 100\)
Bird's array notation \(\{100,8 [1 [2 \neg 2] 2] 2\}\)
Hyperfactorial array notation \(100![1] w/10\)
Fast-growing hierarchy \(f_{\varphi(7,0)}(99)\)
Hardy hierarchy \(H_{\varphi(7,0)}(100)\)
Slow-growing hierarchy \(g_{\vartheta(\varphi(7,\Omega+1))}(100)\)


It is likely pronounced as so:

Tethrahepton (Pronunciation)


  1. Saibian, Sbiis. 4.3.3 - Forging Extended Cascading-E Numbers Part I. Retrieved May 4, 2014.

See also