Well,
Elrond was 58+3,441+3,018=6,517 years old when the four
Hobbits and
Aragorn showed up in
Rivendell. So
Bilbo in 70 years could learn only 1.07% of everything Elrond had learned, obviously ... 🤓
... but hang on, Bilbo left
the Shire on his
111th birthday, in 3001 Third Age. As he probably visited
Erebor before settling down at Rivendell, that was probably only in 3002 TA. That only leaves him 16 years to learn stuff from Elrond there.
Then again, Bilbo returned to the Shire from his first "visit" to Erebor in 2942 TA. That' 78 years before 3018 TA. What's with the 70 years? 🤔🤨