Get the dates right

A guide was taking a party round the British Museum.
'This sarcophagus is five thousand years old.'
A bearded figure with a turban stepped forward. 'You are mistaken,' said Nasrudin, 'for it is five thousand and three years old.'
Everyone was impressed, and the guide was not pleased. They passed into another room.
'This vase', said the guide, 'is two thousand five hundred years old.'
'Two thousand five hundred and three,' intoned Nasrudin.
'Now look here,' said the guide, 'how can you date things so precisely ? I don't care if you do come from the East, people just don't know things like that.'
'Simple,' said Nasrudin. 'I was last here three years ago. That time you said the vase was two thousand five hundred years old.'