[philman_36]

Pre-1965 US coins are about 90% silver. It's fairly easy to convert their value into Fed Notes, based on the coinage, quantity, year, and current spot silver price, at a point of sale or transaction.

Yes, by silver weight. A pre-1965 dime is of far more value than a 2021 dime because of its metallic composition.

[amorphous]

Congress set the value. A fatal flaw in our monetary system, IMO. Same with the value of gold, way-back-when. And nowadays, the value of both gold and silver appears to be artificially manipulated by governments, bullion, and central banks.

Humankind has a knack for creating existential threats to itself for some reason (e.g., government, money, nuclear weapons, electricity, internet, etc.). Some of which, these days, life itself depends upon its existence.