In August 2010, an item began circulating via social media sites and e-mail forwards claiming that the month was something special: An August including five Sundays, Mondays, and Tuesdays happened only once every 800+ years, and 2010 was one of those rare years. Similar claims about months containing five instances of three different days of the week have subsequently been circulated about other months in every year since then:
Those months may be special, but only a little bit — nothing close to 800 years' worth of special. They, as do all months with 31 days, include five occurrences of three days of the week that follow a simple pattern which repeats every several years, as explained below using August 2010 as an example:
Since August always has 31 days, and a week always comprises seven days, August will include five Sundays, five Mondays, and five Tuesdays anytime that month begins on a Sunday (as it did in 2010). And since a week has seven days, and a standard calendar year consists of fifty-two weeks plus one day, August begins on a Sunday an average of once every seven years (not once every 800 or 823 years).
Due to the irregularity caused by leap years, however, August does not begin on a Sunday exactly once every seven years; instead, the phenomenon follows a 6-5-6-11 pattern. That is, when August begins on Sunday, that event occurs again six years later, then five years later, then six years later, and finally eleven years later, whereupon the cycle repeats. Thus we see patterns of Sunday-beginning Augusts in clusters of years like the following:
1965, 1971, 1976, 1982, 1993
1993, 1999, 2004, 2010, 2021
2021, 2027, 2032, 2038, 2049
We're approaching the end of a cycle and thus the longest gap between occurrences, but that gap is a mere eleven years, not eight centuries.
As for the "money bags" canard, while there is a "money bag" in Chinese feng shui, it's an actual cloth bag carried by the Happiness Buddha rather than anything to do with e-mail forwards or the number 5.
To make your own cash-attracting feng shui "money bag," use a colored ribbon to tie nine coins into a square of cloth (both preferably red), then place your "money bag" on or near whichever spot in the house where money is either received or generated. (In other words, if your paycheck comes by mail, place it where you put incoming letters and packages; if your money comes via computer notification of a deposit to an online account, put it near your hard drive.)