100 days after Feb. 1 is May 11 in leap years and May 12 in regular years.
In any given year, the date 100 days before February 1 is October 24 of the previous year.
As of today's date, August 17, 2010, there are 257 days until May 1, 2011.
Subtracting 180 days from February 28, 2016 gives September 1, 2015.
Counting from December 1, 2011, adding 90 days to this date gives February 29, 2012.
September 1, 2010 + 180 days = February 28, 2011.
1st February falls 120 days before June 1st.
100 days before the 1st of May is the 21st of January in a normal year and the 22nd of January in a leap year. 100 days after the 1st of May is the 9th of August.
100 days after January 1 is April 10. January has 31 days, so there are 30 days remaining after January. Then, February has 28 days (29 if it's a leap year), and March has 31 days, totaling 30 + 28 + 31 = 89 days. Adding those to January gives you 30 + 89 = 119 days, meaning 100 days after January 1 falls on April 10.
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Adding 90 days to February 1, 2011 gives May 2, 2011.
The date of the Battle of Singapore was 8-15 February 1942. So it lasted 1 week or 7 days.
100 hours = 4 1/6 days