• Journal of Elementary Mathematics Education in Korea
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• v.21 no.1
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• pp.195-214
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• 2017

The standardized algorithm of natural number multiplication simplify the procedure of arithmetic. In the case of multiplication algorithm with regrouping, we write small the carrying number on the multiplicand. But, teachers and students have to make their own way about the case of two digits multipliers, because Korean elementary mathematics textbooks just deal with the case of the one digit multipliers. In this study, we investigated Korean current elementary mathematics textbooks related to multiplication algorithm with regrouping, and analyzed the result of research on the real condition about marking the carrying number. Besides, we reviewed the guidance contents of algorithm of natural number multiplication in Finland's math textbook and literature. By conclusions, we suggest several implications as followed; First, we need some examples of the way to mark the carrying number in teacher's guidance books and textbooks. Second, teachers try for students to feel the good points of the systematic ways to mark the carrying number. Third, teachers understand algorithm of natural number multiplication and the alternative ways about marking the carrying number.