If I have an Input component bound to a number-type page variable such as
, anything typed in by the user will result in a text string value saved to the variable.
So if I type 1234, what gets saved is actually the string "1234". To treat it as a number in formulas, you should wrap it in the NUMBER function.
Treating this as a bug; Input field should infer its type from the bound variable's type, as well as allow the type to be set explicitly.