top of page

What is Chunking in Primary Maths?


The Chunking Method: 3264 divided by 21 = 155 remainder 9

Chunking is a stepping-stone method to Long Division. It helps children to understand how dividing larger numbers works with divisors (the number they are dividing by), outside their times tables knowledge. It's not necessarily the most efficient method but it does help children to make connections in their learning, work methodically, work down the page (ready for Long Division) and answer more complex questions.

If we go back to those practical experiences of sharing in Maths, children will remember having a pile of objects to share into groups of a particular number. The Chunking Method works on this same principle: taking chunks of the number away, in each row to see what is left. I often describe Chunking using the analogy of a brick wall.


Chunking as an analogy of taking down rows of bricks.

Each brick in the wall is 21 but it would be easier to take away large groups of 21 at a time to find out how many 21s there are in 3264.


This is where children's knowledge of multiples of 10 and 100 play a huge role to working efficiently.


e.g. 21 x 10 = 210

21 x 100 = 2100

Chunking does have its down falls and I have nicknamed it the 'Toilet Paper Calculation'. That's because if it's not carried out efficiently, by taking away the largest chunks possible, the calculation can go on and on. Imagine taking just 210 away at a time from 3264. 11 subtractions later and the only result you have is a bored, tired and confused child who has no idea what the point of this method is. For this reason, I teach children to create 'Fact Files' for their divisor before even beginning to learn the Chunking Method.


Creating a Fact File to jot down multiples

I spend lots of time with children playing around with fact files to get as close as they can to a Target Number.


The first step, is to start multiplying by 2 as this is the same as doubling. This can also help children identify their divisor multiplied by 20, 200 and so on if needed. The second step, is to encourage children to multiply by 10, which leads to multiplying by 100 and so forth.


The third step, is to show them how to find the answer to multiplying by 5 in the easiest way possible. Five is half of ten, therefore if we halve the answer we found when we multiplied by 10, we then know what our number is multiplied by 5.


From those three calculations (x2, x10 and x5), we can work out a multitude of facts:

  • x 7 is the same as the facts for x5 and x2 added together. x 70 is this answer multiplied by 10

  • x 4 is the same as the fact for x2 doubled. x 40 is this answer multiplied by 10

  • x 9 is the same as the fact for x10 minus our divisor (the number we are dividing by)

  • and so on.

It's these skills that make really competent mathematicians. This doesn't happen over night or within one lesson. It's ensuring all the other skills are in place first and that children can see the connections between them. It's also consistent practice and exploration with numbers.


Now we have mastered the fact file we are ready to explore the Chunking Method. Start with dividing by a smaller two digit number at first, like the example below:


Question:

453 divided by 14 =


Step 1 - Draw out the calculation ready (like a Bus Stop with one long side) and jot down the following calculations on the right hand side (fact file):

  • 14 x 2 = 28

  • 14 x 10 = 140

  • 14 x 5 = 70


Step 2 - We are looking to take away the biggest chunk we can at first. Can we find a number bigger than 140 ?

  • 14 x 20 = 280 (Perfect)

  • 14 x 50 = 700 (Too big)

1) Write your biggest chunk under your target number.

2) To the right of the line, write how many lots of your divisor this is.

3) Subtract your chunk to see what you have left.



Step 3 - In this example we have 173 left. Go back to your fact file to find the biggest chunk you can take away next.

  • 14 x 10 = 140 (Perfect)

  • 14 x 5 = 70 (I could save myself time by taking away a bigger chunk)

1) Write your biggest chunk under the number you have left.

2) To the right of the line write how many lots of your divisor this is.

3) Subtract your chunk to see what you have left.


Step 4 - In this example we have 33 left. Go back to your fact file to find the biggest chunk you can take away next.


(You might be starting to see how this could go on forever if children don't work efficiently using their fact file - this is where my toilet paper analogy came from. I see it time and time again, when children do not explore the number facts first. They then become disillusioned with the method and have very little success. Always start with a Fact File).

  • 14 x 1 = 14

  • 14 x 2 = 28

Once you have subtracted your final chunk from your calculation, you may end up with a remainder (a number that is less than your divisor). In this example there is a remainder of 5.


Count up the groups you have noted on the right hand side and add them together e.g. 20 + 10 + 2 = 32 groups of 14.

Answer:

453 divided by 14 = 32 remainder 5


Remember, play with your fact file first to identify the largest chunks possible and avoid the Toilet Paper Calculation.


If you would like to learn more about the methods used within the Primary Curriculum, join my FREE Primary Parents' Community on Facebook for lots of top tips, links and ideas to inspire a love of learning. There is also a Free Times Tables Mat to download in there too.



Happy Chunking

Joanne Adams







Comments


  • Facebook
  • Instagram
  • Amazon
bottom of page