The leap year law translated to English doesn't just say "Every year divisible by 4 has a leap day.", it also says, "Unless the year is divisible by 100, then i

The leap year law translated to English doesn't just say "Every year divisible by 4 has a leap day.", it also says, "Unless the year is divisible by 100, then it's not a leap year". But then it also says "But if it's divisible by 400, it's a leap year again!" So maybe some of the programmers only knew the first 2 rules...