+0
the number of idiopathic and cryptogenic cases are getting decreased. A number of idiopathic and cryptogenic cases are getting decreased.
[in the above two sentences, pls expln whether the verb "is'/are" usage is correct]
+0
What would you think is correct?

BillJ
Comments  
Anonymous The number of idiopathic and cryptogenic cases are getting decreased decreasing. A number of idiopathic and cryptogenic cases are getting decreased decreasing. [in the above two sentences, pls expln whether the verb "is'/are" usage is correct]
With a quantificational noun like “number”, the form of the verb (singular or plural) depends initially on whether the article is the indefinite “a” or definite “the”. The former indicates an imprecise number, so “number” becomes transparent for agreement purposes and it’s the noun in the of- phrase complement that determines the agreement.

By contrast, the definite article “the” indicates a precise number (though the actual number is not given). This makes the NP singular by virtue of having singular non-transparent “number” as head, thus the verb must also be singular.

Your first example has definite “the”, so it follows that the verb must also be singular "is”.

But your second example is ungrammatical. The use here of the indefinite article in “a number” indicates an imprecise number of cases, so to say that some arbitrary number of cases is decreasing makes no sense. But it would be okay if you re-worded it to something like “A number of cases are showing promising results”, where plural "are" is correct.

BillJ