Why is the result of a subtraction of an Int16 parameter from an Int16 variable an Int32? [duplicate]

Answer 1

I think its done automatically done to avoid overflow,

lets say you do something like this.

Short result = Short.MaxValue + Short.MaxValue; 

The result clearly wouldn't fit in a short.

one thing i don't understand is then why not do it for int32 too which would automatically convert to long???