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   78 + 22   90  (70 + 20) Add the tens   10  (8 + 2)   Add the units  100 Vertical Addition by Partition with 3-digit Numbers   555 + 486   900  (500 + 400) Add the hundreds   130  (50 + 80)  Add the tens    11  (5 + 6)    Add the units  1041

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