The last day of the 21st century is Thursday December 31st 2099. The first day of the 22nd century is Friday 1st January 2100.
December 31, 2099!
December 31st, 2009 was a Thursday.
December 31st, 1951 fell on a Monday.
December 31st, 1959 fell on a Thursday.
31st of December is a normal trading day for banks in the UK.
Sunday
31st December
It was a Tuesday.
It was a Monday.
It is December 31st 2009
Hogmanay is celebrated on the last day of the year, which is December 31st.