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"Googolduduex" redirects here. It is not to be confused with googoldudex.

Googolstackstack is equal to $$10\uparrow\uparrow \text{googolstack}$$ or $$10 \uparrow\uparrow 10 \uparrow\uparrow (10^{100})$$.[1] It is also called a googolgoogolduplex.[2] It is equal to a power tower of googol-stack tens.

Aarex Tiaokhiao and Username5243 call this number googolduduex.[3][4]

## Etymology

The name "googolstackstack" can be separated into 3 parts, "googol" and 2 "-stack"s, where "n-stack" means $$10\uparrow\uparrow n$$, so 2 "-stack"s means the operation applying 2 times.

## Approximations in other notations

Notation Approximation
Up-arrow notation $$10 \uparrow\uparrow 10 \uparrow\uparrow(10\uparrow 100)$$ (exact)
Chained arrow notation $$10 \rightarrow (10 \rightarrow 10^{100} \rightarrow 2) \rightarrow 2$$ (exact)
BEAF $$\{10,\{10,\{10,100\},2\},2\}$$ (exact)
Hyper-E notation $$\textrm{E}100\#1\#3$$
Hyperfactorial array notation $$((70!)!1)!1$$
Fast-growing hierarchy $$f^2_3(f_2(324)))$$
Hardy hierarchy $$H_{\omega^32+\omega^2}(324)$$
Slow-growing hierarchy $$g_{\varepsilon_{\varepsilon_{\omega^\omega}}}(100)$$