http://www.nytimes.com/2009/03/17/science/17angi.html?_r=1

And there are plenty of other similarly illuminating examples of memory’s whimsy and bad taste — like why you may forget your spouse’s birthday but will go to your deathbed remembering every word of the “Gilligan’s Island” theme song. And why you must chop a string of data like a phone number into manageable and predictable chunks to remember it and will fall to pieces if you are in Britain and hear a number read out as “double-four, double-three.”

The limits of working memory again encourage our pattern-mad brains, and so we strive to bunch phone numbers into digestible portions and could manage even 10-digit strings when they had area codes with predictable phrases like a middle zero or one. But with the rise of atonal phone numbers with random strings of 10 digits, memory researchers say the limits of working memory have been crossed. Got any index cards?