| 摘要 |
PROBLEM TO BE SOLVED: To solve the following problem in mental arithmetic of two-digit multiplication: when the combination of a multiplier and a multiplicand is particular (for example 90's×90's), the calculation falls within the mental arithmetic ability of an ordinary person (mainly depending on short-term memory ability of seven figures), but when the combination of a multiplier and a multiplicand is general, the calculation exceeds the short-term memory ability of an ordinary person making it impossible to do mental arithmetic. SOLUTION: Figures appearing in any process of two-digit multiplication are divided into blocks of two digits and transformed into words to make the number of words to be simultaneously memorized seven or less so that the calculation falls within the short-term memory ability and the mental arithmetic is possible. In another method, the figures appearing in any process of two-digit multiplication are memorized by calculating the figures using right side and left side of the body and fingers of right and left hand so that the mental arithmetic is possible. COPYRIGHT: (C)2009,JPO&INPIT
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