Calculating average of every nth value [Formula tips]

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Lets say you have a large list of numbers, and you want to calculate the average of every nth value. Not the average of all numbers, but just every nth number.

That is what we will learn in next few minutes.

Few assumptions

Before we jump in to any formulas, first lets assume that all your data is in a table, conveniently named as tbl. Lets say this table has below structure.

Average of every nth value - calculating using Excel formulas.

Also, the value of n is a named cell N.

Average of every nth value

Approach 1: Using helper columns

Average of every nth value - calculated using Helper columnIf you have no allergies towards nuts, dairy or helper columns, then this approach is easiest.

We just add an extra column to our tbl , called as helper.

In the helper column, write this formula.

=MOD([@ID], N)=0

This will fill the helper column with TRUE & FALSE values, TRUE for all nth values, FALSE for everything else. See aside.

Once we have the helper column, calculating average of every nth value is easy as eating every slice of a cake.

We use AVERAGEIF to do this.

=AVERAGEIF(tbl[Value],tbl[Helper],TRUE)

Approach 2: Not using helper columns

Now things get interesting. Lets say you want to calculate average, but not use any helper columns.

First the formula:

=AVERAGE(IF(MOD(tbl[ID], N)=0,tbl[Value]))

Array entered.

Lets understand how it works:

We want the average of every nth item of tbl[Value] column.

In other words, we want average of every item of tbl[Value] column, whose corresponding tbl[ID] value is perfectly divisible by n.

How do we know when a value is perfectly divisible by another?

Don’t worry. You don’t have to do the long division on paper now. Instead we use Excel’s MOD function.

When a value is perfectly divisible by another, the reminder is zero.

So, MOD(value1, value2) = 0 means, value2 divides value1 perfectly.

That means…

We want the average of tbl[Value] when MOD(tbl[ID], N) = 0

Lets write that in Excel formula lingo.

=AVERAGE( IF(MOD(tbl[ID], N) = 0, tbl[Value]) )

This formula results in a bunch of values and FALSEs. Assuming N=3, this is what we get (for sample data):

=AVERAGE({FALSE;FALSE;15;FALSE;FALSE;18;FALSE;FALSE;18;FALSE;FALSE;15;FALSE;FALSE;14; …})

Since AVERAGE formula ignores any logical values, it will calculate the average of {15, 18, 18, 15, 14 … } and returns the answer you are expecting.

As this formula is processing arrays instead of single values, you need to array enter it (CTRL+SHIFT+Enter after typing the formula).

Bonus scenario: Average of FEBRUARY values only!

Here is a bonus scenario. Lets say you want to calculate the average sales of FEB alone… Then you can use AVERAGEIF (or AVERAGEIFS, if you want to have multiple conditions).

=AVERAGEIF(tbl[value], tbl[month], “FEB”)

Averageif() formula example - average of February values alone

Download example workbook:

Click here to download the example workbook. It contains all the techniques explained in this post. Play with the data & formulas to understand better.

Time for some challenges…

If you think averaging every nth value is not mean enough, try below challenges. Post your answers using comments.

  1. Write a formula to calculate average of every nth value, starting at row number ‘t’.
  2. Write a formula to calculate average of every nth value, assuming your table has only value column (no ID column).

Go ahead. Show off your formula skills. Post your answers in comments section.

Improving your Excel batting average

Calculating averages predates slice bread. Folklore says that when first neanderthal figured out how to express numbers and carved 2 of them on a cave wall, his manager walked by and asked “What is the average of these two? Eh?” and thumped her chest.

Although caves & wall carvings are replaced by cubicles & spreadsheets, we are still calculating averages, almost 2.9 million of them per hour.

So it pays to learn a few tricks about Excel Average formulas. Check out below to improve your average:

If your boss is the kind who thumps her chest and mocks you for your poor Excel skills, don’t cave in. Fight back. Enroll in Excel School and show that you can evolve.

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29 Responses to “You are invited [personal]”

  1. Umar says:

    Dear Sir,
    This is to just Wish the kids a Happy birthday in Advance.May Almighty bless them all strength,Success

  2. Nanda says:

    Dear Chandoo,

    My best wishes to your child.I had become regular visitor of your site and finally today it made me to post a comment...

  3. Best wishes from my end! Dont think it would be possible to personally come .. but my best wishes would always be there!! 🙂

  4. bill says:

    Chandoo, thank you for the kind invitation. I wish a special birthday day for your daughters, Nishanth & Nakshatra. Will you be serving "dudh pakh"?
    -bill

  5. Venus says:

    What a kind thought to invite us!
    I pray your family will be continually blessed.

  6. Jerryboy says:

    Thank you very much for the invitation, how I wish Philippines is just a Jeepney ride away from India. Best wishes for your baby girls and more blessings to come.

  7. Francis Chin says:

    Hi Chandoo,

    Thanks for the invitation ! You treat everyone that comes to your site as part of your family community. Me and my family wishes Nishanth & Nakshatra a very very happy birthday !!

    Though physically we cant be with you to celebrate the occasion, you know our blessing are with you !

    To be a father is not easy, furthermore you have to be a father to 2 kids !

    Francis
    Dad of 2 and 9 year old.

  8. Emma says:

    Hi Chandoo,
    It was very kind of you to invite us all along to the 'Extravaganza'. Like others that have commented here I too, am to far (Australia) to pop over for a piece of cake 🙂 Best wishes to you and your family on such a milestone.
    Emma
    (soon to be mum of 1!!!)

  9. Vijesh says:

    Dear Chandoo
    God bless Nishanth & Nakshatra. Wishing you and your family a very enjoyable first birthday party.
    (Father of a 9 month baby... wondering how you manage 2 !!! )

  10. Ninad Pradhan says:

    God bless the little ones. Have a blast.

  11. fred says:

    Hi Chandoo

    Happy birthday !
    Indeed children are a blessing and make our lives much more deeper.

  12. govi says:

    Wow! I wonder how that would look; all those Excel users partying with your cute kids!
    Enjoy the festivities and remember; they grow up really fast.

  13. Ram Kapoor says:

    Dear Chandoo,

    Thanks for your invitation!

    Please accept my wishes for Nishanth & Nakshatra, and a very very happy birthday to both of them.

    (Father of a 1 year old baby)

  14. Vijay says:

    Hi Chandoo,

    Thanks for the invitation. Wishing Nishanth and Nakshatra a very happy birthday and God bless all of you!

  15. Lynn says:

    Howdy Chandoo,
    Gosh, would love to attend the birthday party for your little blessings but I live in Dallas, TX. The children are beautiful. Thank you so much for the Excel information, tips, hints, special formulas, etc., you and your children are really a blessing. I look forward to your e-mails and check your web site frequently. Regards, Lynn

  16. Kalyan Verma says:

    Chandoo Garu,

    Your kids look adorable. Congratulations. My Aashirwaadam to both of them.

    Regards,
    Kalyan Verma

  17. Chandoo says:

    @all: Thank you every one for the wishes, blessings and prayers. We are very excited and busy with the birthday preps now. I will share a pic or two when its over... 🙂

  18. Nilesh Desai says:

    Wish you and your entire family all the blessings. May god provide your babies with all the love and charm in the entire universe.

  19. Helen says:

    Like Emma I am rather far away (South Africa), but best wishes to you and your family on this special occasion.
    (Mother of 7 and grandmother of 5)

  20. Rajatha says:

    Dear Chandoo,

    May God Bless your little ones with Good Health... Happy birthday to them from me... Wish i could be there but work doesn't permit me to travel 🙁

    And thanks again for treating all of us like your family

    Rajatha

  21. saurabh says:

    Sir.

    God bless the two little angels with all the happiness in the world.....

  22. Penny Bradley says:

    Wishing Nishanth and Nakshatra a very happy first birthday. My youngest has just turned 18, and I wish you and your family every happiness in the exciting journey ahead.

  23. Julien G says:

    Hi Chandoo,

    I'm reading your blog for more than a year now, and i'm very pleased by this invitation.
    I wish a very special Happy Birthday to the 2 little ones from Mauritius Island.

    If, for any reason, you are coming on the island in the future, feel free to drop me a mail.

    Have a nice party, and a nice year to come with Nishanth and Nakshatra.

  24. John Franco says:

    Happy birthday!

    Your babies are beautiful!

    This year is not possible for us to attend. My family will be there for your next family party.

    Enjoy the cake and dinner

  25. Pankaj Kumar says:

    May God Bless your little ones with Good Health… Happy birthday to them from me....I am also the father my little daughter named akanksha, she is 2.5 yrs old,,,,but i am unemployed 2 yrs ,,i know when u become a dad u r many hopes.

  26. V S Venkatraman says:

    Guru

    My belated wishes for your kids... I feel sorry for having missed them to wish to the right time.... May almighty shower all his blessings on your family.....

    With regards

  27. Gene Magerr says:

    Chandoo,

    Congratulations. Please give you children a big Happy Birthday (one day late) from me. Enjoy, they grow up very fast

    Gene

  28. Chandoo says:

    @all.. thanks for the wishes and blessings. We had a fantastic weekend with all the relatives, friends. Kids loved the cake, enjoyed the beach and had fun playing with gifts. Here are some photos..

    birthday-morningkids-at-beach

  29. Mick C says:

    Chandoo & family - greetings from Ireland, hope you enjoyed the day!

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