Akira Sadakata

“A thousand single worlds are called a "small-thousand-world." (Small thousand means "one thousand.") In modern terms, this would be a galaxy. One thousand small-thousand-worlds make a medium-thousand world. "Medium-thousand" is dvi-sāhasra (literally, "2,000"), a term used to mean 1,000 [to the second power], that is, a million worlds. One thousand medium-thousand-worlds make a great-thousand world. "Great-thousand" (try-sāhasra, literally, "3,000") denotes 1,000 [to the third power], that is, one billion worlds. A great-thousand-world is also called a "thousand-cubed- great-thousand-world" (try-sāhasra-mahāsāhasro loka-dhātuḥ), or trichiliocosm. These worlds all experience the Buddhist cycle of existence and disappearance together, so they can be called a single unit in term so destiny.”
― Akira Sadakata, Buddhist Cosmology: Philosophy and Origins

“It is a common pattern in Asian religions that hells below complement heavens above. In Buddhism, just as there are many hells, there are countless numbers of devas, and a multitude of heavens, summarized in figure 17.”
― Akira Sadakata, Buddhist Cosmology: Philosophy and Origins