The story of a reconstruction gone awry (a play).

Monk Tosan, an Afghan scribe [arriving at square n=81 in the list], in the atelier:
I think we should not use this number 666, better change it in the middle.
Tosan, who just met with Christian missionaries in Kabul, doubles ...333... to ...646...
Silence follows, then a joke by the bold Buddhist master on this superstitious monk:
I don't want sixes. All evil should be avoided (but what is written must stay).
Tosan does not understand irony and takes up substituting six as a practise, and [at n=82] says:
Look master, this number now doesn't have any sixes at all.
Master spells trouble! Work is stopped and intervention comes from the numerology expert in the team. The bearded sage proposes to introduce an error [at n=83]:
This number magic is needed to maintain the equilibrium...
One digit is changed with the result that as a miracle [at n=86,88,90] the sequence 666 reappears! Also the heretic monk Tosan must make two inverse substitutions [4 to 6 at n=87,92] to pay tribute for his sins.
Buddhist harmony must be ALL embracing, such is the eternal message of the Avatamsaka.

This anecdote is not historical, because the Indian writers as well as the Chinese translators wrote words instead of decimal numbers. Must get back at the publisher about the typos [vertical stripes] and calculation errors [horizontals] in the text.

Or take 10 steps at a time – multiply the exponent by 2^10.

1. 10¹⁰
2. 10¹⁰²⁴⁰
3. 10^10485760
4. 10^10737418240
5. 10^{10995116277760}
6. 10^{11258999068426240}
7. 10^{11529215046068469760}
8. 10^{11805916207174113034240}
9. 10^{12089258196146291747061760}
10. 10^{12379400392853802748991242240}
11. 10^{12676506002282294014967032053760}
12. 10^{12980742146337069071326240823050240}
13. 10^{13292279957849158729038070602803445760}

That last number is Cleary's unspeakable 10^(10*2^120). And more follows at Novaloka.

"In one atom are untold lands, and as in one, so in each." This means that all atoms contain untold lands, and that we can substitute each one of them for that many. Cleary's untold is with 10^(10*2^122) the largest single number name.

The first four verses of this poem are most challenging. They apply a superexponential iteration over an exponential one.

“If untold buddha-lands are reduced to... an unspeakable number of atoms in an instant,
and this continuous reduction [iteration 1] moment to moment goes on for untold ^aeons...

Counting ^aeons by these atoms [iteration 2],
and counting this way for an unspeakable... (number of times).”

Exactly what number heights do these strange over-the-top iterations (or recursions) achieve?
At Novaloka the visions from the Avatamsaka Sutra receive a mathematical formulation. These numbers are proven to increase (at least) through an operation called tetration – the superpower which comes after exponentiation.

The record number (of atoms, lands or aeons) is expressed as a power tower of exponents. The value of the exponents is unimportant. What matters is the tetrational iterator, indicating that the height of the tower here is Cleary's unspeakable.
Remember when powers are piled on top of each other, they are resolved from the top down (else use brackets).

A point the Avatamsaka Sutra often makes at the end of an array of concepts (a number is taken up as a concept – a name to describe an unknown) is, that the astronomically large returns to the atomically small. Here too the last record is embodied (as a number of virtues) by a being (Universal Good), who comes in an unspeakable multitude. Again to be multiplied by all points in the cosmos – a quantity which receives no further specification (are points atoms of space?).
For theoretical physicists the litany of repetitive topologies that follows may hold promise, but our Big number expansion ends here, in the proximity of the enlightening being Universally Good (the bodhisattva Samantabhadra).