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

  98
+ 98
 180  (90 + 90) Add the tens
  16  (8 + 8)   Add the units
 196



Vertical Addition by Partition with 3-digit Numbers

  375
+ 577
  800  (300 + 500) Add the hundreds
  140  (70 + 70)  Add the tens
   12  (5 + 7)    Add the units
  952


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