In my textbook, they have given some applications of Gray codes. One use of Gray code is in Karnaugh maps.

consider a 3 variable k-map

Here Gray codes are used, but why is the decimal equivalent of binary code written in that box instead of the decimal equivalent of Gray code? That is, first row, third column box should be written as 2, right? Since 011 is Gray code, its decimal value is 2. Please clarify this.

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    \$\begingroup\$ There is no Karnaugh-map-police, you are free to scribble any notes in the boxes that makes designing easier for you. I guess the difference between your personal notes and the actual solution must be clear to your teacher though. Mind you the digits are not a formal part of the KM. \$\endgroup\$
    – jippie
    Sep 24, 2015 at 8:24
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    \$\begingroup\$ Agreed. It's not the ideal choice by the text book author to use filler text that doesn't make this obvious; instead of using e.g. a, b, c. \$\endgroup\$ Sep 24, 2015 at 8:29

1 Answer 1


The definition of the outputs shown within a karnaugh map is defined by a forumla or truth table, of which the axis values are the inputs. In this example, 0 1 2 ... has apparently been used as arbitrary filler numbers.

Gray codes refer only to the method by which the axis are labeled.

Here are some clear examples of how the tables are used.


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