If you restrict to months different from february, all of them have at least 30 days and you can easily see that "having" days 1..7 always gives you all the days up to 30 (just write numbers 1..30 putting a newline every 7 of them). Restricting to months from march to december (which always present the same pattern, whatever year you consider after the transition from Julian to Gregorian calendars) you can quickly check that all days 1..7 are there for all days of week (it suffices to see it for only one of them, then that's only a matter of modulo-7 maths).

So the only one that remains tricky is 31, because not all months "support" it.

Flavio
perl -ple'$_=reverse' <<<ti.xittelop@oivalf

Io ho capito... ma tu che hai detto?

In reply to Re^3: How preparing the weekly shift roster led to a fascinating discovery... by polettix
in thread How preparing the weekly shift roster led to a fascinating discovery... by McDarren

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.