Ask them what methods you can call on 1 in Java.

As Scott was getting at, 1 is a primitive, not an object.

By contrast in a TRUE object-oriented language like Smalltalk or Ruby, 1 IS an object and you CAN call methods on it. Heck, in Ruby if you want you can even add methods to class FixNum and then call them on individual numbers.

Cheers,
Ben