Mersenne: Richard's Y2.1K error !!

[Dave Mullen]

Ironic you should mention this, and then make the most common omission.   From the top, the rules are ...   If year / 100 then leap year If year / 400 then not leap year If year / 1000 then leap year   2000 was a Leap Year, as will be 3000 and 4000. Although, as the world's spinning is slowing down, maybe we'll need a fourth condition at some point in the future ?   Dave