| 摘要 |
PROBLEM TO BE SOLVED: To provide a blackboard with which the troublesomeness of working in matching between a date varying every month and date of the week can be removed and they can be easily coincided while a numerical operation of required items produced with the lapse of time duration becomes quite obvious. SOLUTION: The blackboard is mounted so that one surface of a heptahedron 1 is displayed at the position of date of the week below a date. A date varying every month and date of the week can be easily coincided and hold by pivoting the heptahedron 1 up to the surface where a date and date of the week coincides by using a tab 2 and hooking it at the coincided surface. A user can perform the numerical operation for the items written down on an item plate 9 by operating a counter 17 using a solar cell 10 as a power supply. COPYRIGHT: (C)2004,JPO
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