72 + 89 = 161 |
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Make 72 (2 ONES and then 7 TENS) |
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Add 9 ONES. But there are only 8 ONES. So add 8 ONES . . . |
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Then swap, trade, or regroup 10 ONES for 1 TEN. Now you can add the remaining ONE to make 9. |
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Add 8 TENS by first adding 2 TENS. Next trade 10 TENS for 1 HUNDRED. Then add the rest (6) of the TENS. Read the answer 161. |
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