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   45 + 16   50  (40 + 10) Add the tens   11  (5 + 6)   Add the units   61 Vertical Addition by Partition with 3-digit Numbers   453 + 780  1100  (400 + 700) Add the hundreds   130  (50 + 80)  Add the tens     3  (3 + 0)    Add the units  1233

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