# How many possible prime implicants are there in total for a 4-variable Karnough-map? [closed]

The answer for this question is 81. But I count figure out why. Can someone explain to me how does this work. Thank you.

• What have you tried? We expect you to make a serious effort on your own and show us in the question what you have tried; otherwise it is hard to give you feedback. Do you understand what a Karnough-map is and what a prime implicant is? Have you tried working out how many there are for a 1-variable Karnough-map, a 2-variable Karnough-map, a 3-variable Karnough-map? Have you tried asking your teacher? – D.W. Oct 2 '14 at 17:38

Hint: $81 = 3^4$. So each variable can appear in a prime implicant in three different forms. Can you figure out which?