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What day of the week was 1 January 2000?

calendarmodular-arithmeticleap-years

1 January 1900 was a Monday. Using only that fact and the rules for leap years, find the day of the week of 1 January 2000.

Then say why the same calculation from 1 January 2000 to 1 January 2100 gives a different shift.

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Count the days between the two dates: 100 years of 365 days plus one day for each leap year. Then take the remainder when divided by 7.

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