There may not be any mention in the Tipitaka, but look at what was written 3 years ago:
Download a copy for keeping…
The Human Brain vs. Supercomputers… Which One Wins?
or view at the webpage…
The Human Brain vs. Supercomputers… Which One Wins?
In the above webpage, it is mentioned that:
“In contrast, our miraculous brains operate on the next order higher. Although it is impossible to precisely calculate, it is postulated that the human brain operates at 1 exaFLOP, which is equivalent to a billion billion calculations per second.”
Much metta.