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*You can also download the PDF version of this game to file away for later ***on TeachersPayTeachers**

You can do this activity with your students at the board or on worksheets.

Provide them with a really long horizontal sum. Something like this:

3 + 11 + 7 + 5 + 5 + 4 + 9 + 1 + 2 + 13 + 8 =

The idea here is to group pairs of numbers into tens or multiples of ten so that they can quickly and easily find the sum using mental math.

Here there are four pairs that yield 10: (3 + 7); (5 + 5); (9 +1); (2 + 8) so that total is 40 plus 11 + 4 + 13 = 28

So the total sum is 40 + 28 = 68

Students who are agile with this will come up with other ways to get the same answer.

For example: (7 + 13); (11 + 9) = 40

Then, (5 + 5); (3 + 4 + 1 + 2) = 20

Then, add 8

So the final sum is 40 + 20 + 8 = 68

If they are working on worksheets, challenge them to find at least three different ways to use mental math to get the same sum.

*You can also download the PDF version of this game to file away for later ***on TeachersPayTeachers**

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