The terrible terrible terrible tethriterator is equal to E100(((#^^>#)^^#)^^#)^^#100 using Extended Cascading-E Notation.[1] The term was coined by Sbiis Saibian.


The name of this number comes from the prefix "terrible" and the number terrible terrible tethriterator.

Approximations in other notations

Notation Approximation
BEAF ???
Bird's array notation ???
Fast-growing hierarchy \(f_{\varepsilon_{\omega+3} }(100)\)
Hardy hierarchy \(H_{\varepsilon_{\omega+3} }(100)\)
Slow-growing hierarchy ???


  1. Saibian, Sbiis. 4.3.7 Extended Cascading-E Numbers Part IOne to Infinity. Retrieved 2017-03-01.
Community content is available under CC-BY-SA unless otherwise noted.