App Academy

Boolean Algebra Pratice

Hi, I am trying to find an understanding of what the X means in the Kmap. Can anyone explain this to me or give me a link to a Youtube video Thanks a bunch.
@jbyers @bryanray

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Good morning!
Those X cells represent the “Don’t Care Condition” in the K-map. Essentially, you can treat them as 1s if they help you to make your groupings. You shouldn’t need to worry about this case for the assessment, but here is a short video that goes through an example.
I hope this is helpful for you!

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At any section does this subject exist in the course?!

Good morning!
Thank you very much @jbyers. That helps a bunch. I don’t like not understanding everything that I’m working with so yes that helps. Have a great day. And also just to clarify, since I can consider them as 1’s then I can group them with the 1’s as well? I can also just replace them with 1’s and not write the X? Thank you for your clarification.

Hi, it came up in the Boolean practice excercise #2 and I was just trying to understand what this x meant. But Mrs. Byers posted a video link in her reply so I am going to go and look at it now. Hope this helps.


Yes, you can group them with 1s. I would recommend keeping them as Xs on the page rather than changing them to 1s, but you can assume they act like 1s in your groupings.

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Hi @jbyers. @bryanray sorry to bother you again, however there is something else that is really confusing me with the Boolean Algebra. Okay so in the YouTube video
as far as the Kmaps, it was explained very simple, however, in this screen shot…

you find that all the variables are being used. I am arriving at the same answer but I am also not understanding why we are using all these variable when we don’t have to.

so for example, I answered the above question by simply selecting Row 2 as the first group, making X. Then I chose the top two 1s as a group and made which had the common variable being the Y which was 0 so I then used a NOT operator and came up with the same answer but without all the extra work. Is it necessary that I perform these same operations if I come up with the same answer?