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

  90
+ 74
 160  (90 + 70) Add the tens
   4  (0 + 4)   Add the units
 164



Vertical Addition by Partition with 3-digit Numbers

  689
+ 217
  800  (600 + 200) Add the hundreds
   90  (80 + 10)  Add the tens
   16  (9 + 7)    Add the units
  906


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