Difference between quantum and quantus, -a, -um
In Orberg LLPSI in Cap 8.72 he has Medus asking the shopkeeper to show him a ring:
Medus: “Ille post te. Quantum est pretium illius anuli?”
Orberg explains: quantus, -a, -um = quam magnus
then in cap 31.53 we have Cornelius asking Iulius how much Medus has stolen: “Quantum pecuniae abstulit”
Orberg explains: Quantum = quam multum
Each of these two uses has an separate entry in the vocabulary. What’s the difference between them?
Quantum can mean both ‹how much› and ‹how many›?
Linguistically, they are the same word but, as often in Latin, the neuter singular form can take on a life of its own.
quantum pretium: quantum here is an adjective modifying the noun, “what price?” “how great price?”
quantum pecuniae: here pecuniae is in the genitive, and the word quantum is being used on its own as a neuter noun, not as an adjective: “how much (of) money?” - the answer could be: multum pecuniae! a lot of money!
Like quantus, multus is an adjective where the neuter form - multum - is often used on its own with a partitive genitive, and it can also be used adverbially. If you look in a dictionary like Lewis & Short, you will see that the entry both for quantus and also for multus have sections devoted to the special uses of the neuter singular forms; this is true for lots of Latin words where the neuter singular has developed its own special uses:
http://athirdway.com/glossa/?s=quantus
http://athirdway.com/glossa/?s=multus
Belated thanks for this..