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Use counters to add 10 + 2.
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You add:
Which counters show the sum?
Use counters to add 10 + -4.
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Which counters show the sum?
Use counters to add 9 + -5.
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Which counters show the sum?
Use counters to add 4 + 10
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Which counters show the sum?
Use counters to add 11 + 1.
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Which counters show the sum?
Use counters to add 3 + 3.
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You add:
Which counters show the sum?
Use counters to subtract -4 - 6.
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You subtract:
Which counters show the difference?
Use counters to subtract -1 - 10.
You start with:
You subtract:
Which counters show the difference?
Use counters to add -9 + 2.
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You add:
Which counters show the sum?
Use counters to add -10 + 5.
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You add:
Which counters show the sum?
Use counters to subtract -2 - 11.
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You subtract:
Which counters show the difference?
Use counters to add 3 + -10.
You start with:
You add:
Which counters show the sum?
Use counters to subtract 5 - -5.
You start with:
You add:
Which counters show the difference?
Use counters to add 5 + -5.
You start with:
You add:
Which counters show the sum?
Use counters to subtract 5 - -10.
You start with:
You subtract:
Which counters show the difference?
Use counters to add -5 + 6.
You start with:
You add:
Which counters show the sum?
Use counters to add 6 + 4.
You start with:
You add:
Which counters show the sum?
Use counters to subtract 3 - 1.
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You subtract:
Which counters show the difference?
Use counters to subtract 2 - -1.
You start with:
You subtract:
Which counters show the difference?
Use counters to add 6 + -6.
You start with:
You add:
Which counters show the sum?
Use counters to subtract -6 - 1.
You start with:
You subtract:
Which counters show the difference?
Use counters to add -1 + -2.
You start with:
You add:
Which counters show the sum?
Use counters to subtract 3 - -3.
You start with:
You subtract:
Which counters show the difference?
Use counters to add -2 + -3.
You start with:
You add:
Which counters show the sum?
Use counters to subtract -1 - 3.
You start with:
You subtract:
Which counters show the difference?