Number theory

This morning in the car:

Prince #2:  Mommy - what the highest number?

Me:  there is no highest number

P2:  yes there is

Me:  no honey, you can keep counting forever

P2:  to 9 billion?

Me:  sure...even further

P2:  no - that would take too long.  I think that 9 billion is the very last number.

Me:  what happens if you add one to 9 billion?

P2:  then you have one plus 9 billion

Me:  and that number is?

P2:  Mo-om.  it isn't a number.  9 billion is the last number!

Me:  do you want to count to 9 billion?

P2:  I can do it quick...1 billion, 2 billion, 3 billion, 4 billion, 5 billion, 6 billion, 7 billion, 8 billion and 9 billion

Me:  what about 10 billion?

P2:  Mommy - now you're just being silly.  But you know what Mommy?

Me:  what sweetie?

P2:  I love you 9 billion evers! (this is an offshoot of "I love you forever" which he thinks means "I love you four evers")

Cue the Mommy-tears.  I'll straighten him out on the whole "number thing" later.