This week has no cool number dates. 

But we can use the time to explain how to determine which day of the month will be a half-back day. 

Recall that Half-back days are named in honor of all the retirees who move from Northern states (Michigan, Minnesota, New York, etc) to Florida, find out Florida is too hot, and then move to middle ground in Tennessee or North Carolina or around there someplace.

So, start at the month, go to the day, and come half way back to the year.

If the integers for month / day / year are m/d/y, then the problem is to solve for d when m and y are  known.  The one equation we need is:

                d – y = (d – m)/2

                2( d – y ) = d – m

                2d – 2y  = d – m

                d = 2y – m

For next month, m is 7 and y is 13, so the half-back day is 26 – 7 = 19.  Since each succeeding month value for the rest of the year increases by 1, the half-back d decreases by 1:

                8/18/13

                9/17/13

                10/16/13

                11/15/13

                12/14/13

For the next week with no cool number days (8/25/13), we will examine when the half-back days will end this century.