We do not know, when will the "universal" or "world" calendar be passed and introduced. It probably won't happen soon. Considering that, we offer you "perpetual calendar". It will give everyone an orientation in both the past tense, and the future.
On its basis, it can be determined mechanically:
• Days of the week, when you know the year, month and day (e.g.. 7 XII 1958).
• Dates per month, when you know the year, month and day of the week (e.g.. December, Sunday, 1958).
• Month, when you know the day of the week, day of the month and year (e.g.. Tuesday, 12, 1905).
• Year, when you know the century, day of the week and day of the month (e.g.. Friday, 13 May, 19…).
• Centenary, when you know the last two digits of the year, day of the week and day of the month (e.g.. Thursday, 7 II, ..22).
In a word - so simple, in fact, task with one unknown, that anyone can easily solve, using tables.
Here is an example:
What day of the week falls on the date 7 XII 1958? On board I we find the letter corresponding to the year 1958 - at the intersection of the column 1900 (downstairs) and poem 58 (on the side). It will be the letter E. Look for it on board II 7 XII and we go vertically down to the level of the letter E (on the side). It will be Sunday.
So - a day 7 XII 1958 it was sunday.
Of course, you have to remember about leap years. They are marked on table I with two letters; first for January and February, the second - for the remaining months.
The "perpetual calendar" can serve a lifetime. It enables not only historical dates to be established, but also future ones.
"Perpetual calendar" - is independence from annual calendars.
In a word - for the stingy, thrifty, forewarned, practical and who like law and order!