Note that the NZ function returns a Text (String) result
If I'm not mistaken,
Nz returns the variant if the variant is not null.
Nz returns the value_if_null if the variant is null.
So if the variant is not null and is text, it returns text data type. If it's numeric, it returns a number, and so on.
This NZ(Query1.CountofAcctno,0) will return the number zero if CountofAcctno is Null.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.