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   99 + 57  140  (90 + 50) Add the tens   16  (9 + 7)   Add the units  156 Vertical Addition by Partition with 3-digit Numbers   712 + 931  1600  (700 + 900) Add the hundreds    40  (10 + 30)  Add the tens     3  (2 + 1)    Add the units  1643

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