21 加法 21 等于多少？
21 + 21 = 42
21加法21 等于 42
竖式演算
验算
- 用减法验算：42 − 21 = 21
- 用减法验算：42 − 21 = 21
相关题目
21 + 20 = 41
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21 + 24 = 45
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21 + 25 = 46
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20 + 21 = 41
22 + 21 = 43
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2 + 40 = 42
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