Entry Nº 013Stage 1 · Grades 1–2数与代数
进位与退位
满十进一、退一当十——多位数加减的算理。
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Definition
个位相加满十，就向十位进一；个位不够减，就从十位退一当十。进位和退位不是新规则，只是十进制「满十进一」在计算里的自然表现。
Where it comes from · where it goes
Prerequisites
What builds on it