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   53 + 77  120  (50 + 70) Add the tens   10  (3 + 7)   Add the units  130 Vertical Addition by Partition with 3-digit Numbers   421 + 102   500  (400 + 100) Add the hundreds    20  (20 + 0)  Add the tens     3  (1 + 2)    Add the units   523

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