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   55 + 94  140  (50 + 90) Add the tens    9  (5 + 4)   Add the units  149 Vertical Addition by Partition with 3-digit Numbers   831 + 944  1700  (800 + 900) Add the hundreds    70  (30 + 40)  Add the tens     5  (1 + 4)    Add the units  1775

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