come again vs how's that

come again

intj
  • Used as a polite farewell to a visitor, inviting a return visit. 

  • A polite formula used when one has not heard or understood what has been said, or to indicate surprise. 

how's that

phrase
  • Used to make an appeal to the umpire as to whether the batsman is out or not 

  • Used to ask someone to repeat something 

  • Used other than figuratively or idiomatically: see how, is, that. 

How often have the words come again and how's that occurred in a corpus of books? (source: Google Ngram Viewer )