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

  16
+ 55
  60  (10 + 50) Add the tens
  11  (6 + 5)   Add the units
  71



Vertical Addition by Partition with 3-digit Numbers

  689
+ 201
  800  (600 + 200) Add the hundreds
   80  (80 + 0)  Add the tens
   10  (9 + 1)    Add the units
  890


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