During these steps, some digits are selected for specific roles (e. g., first addend) in the addition operation, while the others are held in working memory, but not used in the current operation.
在这些心算步骤中，每个时刻只有一些数字被特殊地选择用于加法运算的被加数，而其他的数字则仅仅保存在工作记忆中并不用于当前操作。
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