Only quants can have fun with dates that doesn’t involve snogging.
Financial expert/blogger David Markel defines a special birthday as one where you can create a simple math equation from the date.
For example, David was born Dec. 5, 1960. That, of course, is 12/5/60, and 12 x 5 = 60. There are also special days for:
- Addition (1/1/02 is an example)
- Subtraction – (12/5/07)
- Division – (8/1/08)
Fun idea, right? Not sure how you count European dating, where the date precedes the month, i.e., 12/5/07 would be 5/12/07.
Brushing that aside, here’s the big question: Over a 400-year arc (has to be 400 to properly handle the leap-year cycle), how many birthdays are special?
The answer, and the methodology, are here.
Actuarial Opinions 