The eight-ex-terrible tethriterator is equal to E100#^^#>(#+#)8 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 seven-ex-terrible tethriterator.

Approximations in other notations

Notation Approximation
Fast-growing hierarchy \(f_{\varepsilon_{\omega+8} }(100)\)
Hardy hierarchy \(H_{\varepsilon_{\omega+8} }(100)\)


  1. Saibian, Sbiis. 4.3.7 Extended Cascading-E Numbers Part IOne to Infinity. Retrieved 2017-03-01.
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