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

  10
+ 87
  90  (10 + 80) Add the tens
   7  (0 + 7)   Add the units
  97



Vertical Addition by Partition with 3-digit Numbers

  913
+ 865
 1700  (900 + 800) Add the hundreds
   70  (10 + 60)  Add the tens
    8  (3 + 5)    Add the units
 1778


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