Use the calendar page shown and the leap-year rules for century years. On which day of the week will 1 January 2101 fall?

1 January 1901 is a Tuesday. The 200 years 1901–2100 contain 49 leap years (2000 is a leap year, 2100 is not), so they give $200+49=249\equiv 4$ odd days. Tuesday + 4 = Saturday. (Sunday counts 2100 as a leap year; Friday skips 2000.)