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Adding Three-digit Numbers

In the following exercise, you will add a pair of three-digit numbers.

Things to remember:

  1. The numbers are stacked on top of each other, so that the numbers in the one’s place are in the far-right column.
  2. The numbers in the ten’s place are in the middle column.
  3. The numbers in the hundred’s place are in the left column.


  1. Start by adding the one’s place column.
    • If the number is larger than 9, then you need to write the one’s place number and then “carry-over” the ten above the ten’s place column.
  2. Now add the ten’s place column (don’t forget to add any tens that were carried over).
  3. Finally add the hundred’s place column (don’t forget to add any hundreds that were carried over.)

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