Annabelle :: (from the carseat) What is five plus five?
Me :: Use your fingers.
Annabelle :: (fumbling around) TEN!
Me :: (speechless)
Annabelle :: That means two fives are ten!
Me :: Yes.
Annabelle :: How many is four plus two?
Me :: Use your fingers!
Annabelle :: SIX!
(pause)
Annabelle :: If two fives are ten, then how many is two tens?
Me :: You can use your fingers for that too.
Annabelle :: One... two... three... four... five... six... seven... eight... nine... ten... eleven... twelve... fourteen... seventeen... eighteen... twenty... thirteen... twenty three... twenty one...
(looking very surprised and satisfied)
Annabelle :: Two tens is TWENTY FIVE!