• Maki Ishii, Kazumi Hirayama, Keiko Saito, and Daisuke Komatsu.
• Department of Rehabilitation, Shioda Hospital, 1221 Idemizu, Katsuura City, Chiba 299-5235, Japan.
• Brain Nerve. 2009 May 1;61(5):607-13.

AbstractIn Japan, the multiplication table is learned predominantly by rote learning of reciting multiplication table (which is named Kuku) with a standardized mnemonic rhymes. The Kuku is memorized intensively by oral repetitions. Therefore, it is not clear whether the neuropsychological features of the deficit of the Kuku and that of the multiplication table in Western countries after brain injury are the same or not. Here we report the case of a 58-year-old right-handed man who suffered from an inability to perform calculations following right putaminal hemorrhage. His acalculia was caused, for the most part, by his failure to retrieve the Kuku, as well as his confusion over the positions of "0" when he wrote multiple-digit numbers. An analysis of his errors of the Kuku showed strong problem-size effect, which has been found not only in the studies of multiplication deficits both in patients and healthy subjects in Western countries, but also in the Japanese studies on children. Our patient applied the commutative law of multiplication and ordinal number line etc. to compensate for his deficit. Such compensation with preserved conceptual knowledge has also been previously reported in Western patients. Moreover, our patient did not make any errors when the first operand of the Kuku was 5. Sparing of multiplication errors when the first operand is 5 has been reported in another Japanese case study on acalculia as well as in studies of healthy Japanese children; however, this has never been reported in Western studies. Therefore, it was suggested that there were similarities as well as differences between the deficits of multiplication table in Western and Japanese patients after brain injury.

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