These two New Year leaves are exactly 100 years apart. How many odd days are there in the 100 years from 2001 to 2100?

100 years contain 24 leap years (2100 is not a leap year), so the days are $100\times 365+24=36$ 524 = 5217 weeks + 5 days: 5 odd days. That is why Monday moves to Saturday. (6 wrongly treats 2100 as a leap year.)