"What is the phone number of the hospital?"
To say "duo shao" sounds very strange to me. I speak Cantonese and some Mandarin. Have never heard it said this way among native speakers (outside China). Is this how it's actually said by some people?
I study Mandarin and have lived in mainland China, I've never heard or read 多少 in this context.
Not wrong. Indeed telephone number does nothing in quantity, and we say 甚麼 for phone number more than 多少.
it is correct, '多少'means ‘’how much‘， 什么 means ‘what’， so sometimes they are exchangeable but mostly not。 here you can use both
sorry but i'm living in china and duoshao is not correct for phone number, it is effectively for quantity. Plus the way they chinese people tell the phone number make even more incorrect to use "duoshao". They say it one digit after another.