Sunday, January 3, 2010

When Is a Year a Leap Year?

Triggered by the preceding post, an afterthought:

Do you know how to tell whether a year is a leap year? Or do you only *think* you know?

Here's how it goes: A year is a leap year if
  • It is evenly divisible by 4
    • but not evenly divisible by 100
      • unless it is evenly divisible by 400
        • and not evenly divisible by 4000 (Gotcha!)

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