Type of Zero(), One()...etc in Arithmeric class

Hi:
I wonder why "Double" type is used in creating Zero(), One(),... constants in Arithmeric class. I think the minimum  numeric type "Int16" should be used so that it will not affect the type of the original Expression. For example, If I tried to multiply 0*1 constant Int32 expression using Arithmeric.Multiply it will return zero but in Double typec not in int32 type.
