Addition by Partitioning




Worked Examples of Addition by Partitioning

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In Years 3/4 children start to lay out numbers to be added vertically, to get ready for the introduction of column addition typically in Years 5/6.
When two-digit numbers are to be added, children are usually taught to add the tens first which gives a rough answer, and then add the units and add those to the total of the tens.
For three-digit numbers, the hundreds are added first, then the tens, and then the units.


Vertical Addition by Partition with 2-digit Numbers

  62
+ 83
 140  (60 + 80) Add the tens
   5  (2 + 3)   Add the units
 145



Vertical Addition by Partition with 3-digit Numbers

  984
+ 921
 1800  (900 + 900) Add the hundreds
  100  (80 + 20)  Add the tens
    5  (4 + 1)    Add the units
 1905


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