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 + 85   90  (10 + 80) Add the tens    5  (0 + 5)   Add the units   95 Vertical Addition by Partition with 3-digit Numbers   873 + 577  1300  (800 + 500) Add the hundreds   140  (70 + 70)  Add the tens    10  (3 + 7)    Add the units  1450

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