Chunking in mathematics helps pupils to really understand the numbers they are adding as well as helping to develop strategies for mental maths.
Chunking means breaking larger numbers into smaller chunks, separating units, tens, hundreds etc., to make calculations easier.
For example:
45 can be chunked to 40 + 5
126 can be chunked to 100 + 20 + 6
1253 can be chunked to 1000 + 200 + 50 + 3
our sum is
56 - 23 =
this is the same as
50 + 6 - 20 + 3
in order to subtract we need to write the sum vertically
56 = 50 + 6
23 = 20 + 3
Subtract the units first
6 - 3 = 3
then subtract the tens
50 - 20 = 30
then add the answers together
30 + 3 = 33
our sum is
158 - 134 =
this is the same as
100 + 50 + 8 - 100 + 30 + 4
in order to subtract we need to write the sum vertically
158 = 100 + 50 + 8
134 = 100 + 30 + 4
subtract the units first
8 - 4 = 4
subtract the tens next
50 - 30 = 20
subtract the hundreds
100 - 100 = 0
add the answers together
0 + 20 + 4 = 24
so
158 - 134 = 24
our sum is
242 - 128 =
this is the same as
200 + 40 + 2 - 100 + 20 + 8
in order to subtract we need to write the sum vertically
242 = 200 + 40 + 2
128 = 100 + 20 + 8
we need to subtract the units first but we cannot take 8 away from 2
so we need to change the 40 into 30 + 10
we can then add the 10 to the 2 to make 12
242 = 200 + 30 + 12
128 = 100 + 20 + 8
we can now do our sum, starting with the units (including the borrowed 10)
12 - 8 = 4
subtract the tens next
30 - 20 = 10
subtract the hundreds
200 - 100 = 100
add the answers together
100 + 10 + 4 = 114
so
242 - 128 = 114
Harvard Reference for this page:
Heather Y Wheeler. (2015). Subtracting by Chunking. Available: http://www.tiffanymacbeth.com/Maths/chunking_subtraction.htm. Last accessed
Place Value Adding Number Bonds Mental Addition Adding by Chunking Column Addition Subtracting Subtracting by Chunking Column Subtraction Mental Subtraction Roman Numerals
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