| 摘要 |
<p>A calendar is made with thirthy-one sheets of paper, each carrying a number from 1 to 31. In addition each sheet has the names of the months and the days of the week arranged in three columns above the number. As an example, the sheet carrying the number 17 has the day of the week written opposite the name of the month on which the 17th day of that month falls during the year for which the calendar is valid. This type of calendar obviates the need for replacing the sheets carrying the dates and names of months and days.</p> |
