James Carville, while advising Bill Clinton for his second run for the presidency, had two edicts. Stay on point, count off your arguments supporting your point in threes. Using fingers is optional. Psychologically, three gives the listener, reader, whatever, more than an "either-or" decision path. Options and flexibility make it easier for the audience to come to a decision they (he/she/they) feel they have made independently. When the listener comes to their own conclusion, the impression left in their mind is far stronger and more durable over time. Think about this in terms of advertising.
Thirty seven, a prime number, has many magical associations. The most fetched I read, (Scientific American a while back) was as a decision making tool. Say you want to hire the best possible job candidate from a pool of applicants. Line up thirty-seven good resumes, start interviewing with thirty-eight and hire the first good prospect. Your chances of getting a good employee go up 300 plus percent. But who's got the time? In this economy though, you'll likely have the applicants. (see next paragraph)
Another SciAm citation: Miracles. If you divide your life into five minute segments, probability says you are likely to experience six miracle-like episodes each year. Something such as humming a tune and then hearing it when you turn on the radio counts.
It is said that it takes doing something thirty times in a row to make it a habit. It's cold where I live. A suggested method for resetting your body's thermostat to better accommodate sub zero days is to sleep outside (in a nice, down sleeping bag of course) for two weeks and you will better tolerate cold for the rest of the (long) winter.
Here's one I won't test. Told to me by a guide who runs rafts down the Colorado River, after 26 or so days not washing your hair, it attains a natural, washed glow on it's own. That could explain those beautiful savages in movies.
With marketing research, don't base your entire decision making on surveys, focus groups or the like. Never base more than thirty percent of your decision on research—no matter how thorough you think you have been.
This is just a rule of thumb but it gets clients thinking about their assumptions about media. Thirty percent of the paid subscribers to a periodical (and this may be even more likely with electronic media) don't see a given issue of a publication. Issues are lost in the mail, lost in the household, go under the porch, get to the bottom of a large stack of other stuff. Or, the readers are sick, on vacation, bored, angry, whatever—and don't bother to open the publication.
Finally, lists—odd numbers, three or five for talking points on brochures for candidates or causes when you are trying to change people's minds. I have done many campaigns and this rule has not failed. Then again, maybe I just picked the right causes and candidates.