In the Acintita Sutta AN 4.77, the Buddha advised not to ponder too much about four things:
“There are these four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them. Which four?
“The Buddha-range of the Buddhas is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.
“The jhana-range of a person in jhana…
“The [precise working out of the] results of kamma…
“Conjecture about [the origin, etc., of] the world is an unconjecturable that is not to be conjectured about, that would bring madness & vexation to anyone who conjectured about it.
“These are the four unconjecturables that are not to be conjectured about, that would bring madness & vexation to anyone who conjectured about them.”
So, the Buddha range of a Samma Sambuddha is unfathomable to us!!!
But still, for arousing faith and confidence in the Triple Gem, the Tathagata himself performed unrealistic miracles which only a Samma Sambuddha can do!!!
He is also OMNISCIENT, the possessor of all knowledges, mundane and supermundane.
He acquired all this by perfecting the “ten paramis” through many many many eons, which itself is unfathomable to us!!!
The time it takes to perfect all the paramis to its ultimate level is enormous.
Hope you get an idea about the magnitude of such a task!!!