Generally what they have in mind with stuff like this is a few logic gates. Real, real basic. Just a click above what Eric said:
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Ron
Just a click mind you.they buy an Abacus or Slide Rule
Ron