To back up the test results of the first test. (Same as recounting)
Never, unless the calendar is revised in such a way as to start below that number. It would still not repeat the year, just the number.
yes.
Irrational numbers can not be repeating decimals. Any number that is a repeating decimal is rational.
The year 2000 was a leap year and had 366 days and starts on a Saturday. This list of years have a common starting weekday and equal number of days to 2000: 2000, 2028, 2056, 2084.