12
From February 25, 2012 to June 23, 2012 is 17 weeks, so there are 16 full weeks between the dates.
about 33 weeks
19 weeks and 5 days.
33 weeks and 1 day.
28 weeks.
21.6 weeks
Including the start and end dates in the calculation, there are 20 weeks 2 days between the two dates.
26 weeks
There are 12000825 full weeks after February 25 of 2012 and before June of 232012 (unless we change calendars, which I'm sure we will if we don't drive ourselves to extinction first, because the Gregorian calendar's pretty stupid).
About 78 weeks between June 2009 and December 2010.
17
June 4