52

52

52 weeks and one day - plus another day in leap years.

There are 52 weeks in a year.

I assume we are talking about the planet Earth and its usual 7-days weeks and 365 1/4-days from the gregorian calendar. Depending on how you are counting, the number of weeks in a year could vary from 53 to 54. 1) We use to learn at school that there are 52 weeks. There are - 52 weeks and 1 day on regular years - 52 weeks and 2 days on leap years However, it depends on what you are calling a week. If you define a week as an intervall of 7 days, this answer will apply. 2) If you define a week as an intervall of 7 days starting on a particular day, for instance on a Sunday, it will not apply. For instance, regular years starting on a Sunday or a Saturday contain entirely 52 weeks. But those starting on another day would only contain 51 weeks entirely. 3) In another definition, any week is considered as associated to a particular year: each week is associated with the year in which Thursday occurs: "Weeks in a Gregorian calendar year can be numbered for each year. This style of numbering is commonly used (for example, by businesses) in some European and Asian countries, but rare elsewhere. ISO 8601 includes the ISO week date system, a numbering system for weeks; each week is associated with the year in which Thursday occurs (so that if a year starts in a long weekend Friday–Sunday, week one of the year will start after that). Thus, for example, week 1 of 2004 (2004W01) ran from Monday 29 December 2003 to Sunday, 4 January 2004. The highest week number in a year may be 52 or 53. The numbering system in different countries may deviate from the international ISO standard. There are at least six possibilities" Source and further information: http://en.wikipedia.org/wiki/Week#Week_number In this case, a week can have 52 or 53 weeks. 4) In some software applications, some years have even 54 weeks: "Many software applications define a "week-of-year", also known as "fiscal week" or "calendar week", which is used for a variety of purposes. Usually, such weeks are defined as starting on Sunday and ending on Saturday (This differs from the ISO standard, of course ... but that doesn't change the fact that many programs (and human calendars) treat Sunday as the first day of the week.) This paper deals with a Y2K problem that surfaces when a Sunday-starting week is used. A normal year has 53 weeks, where 51 or 52 are "complete" weeks, and 1 or 2 are "incomplete" (or "partial"), since they start or finish in the prior or following year. For example, 1999 has 53 weeks. The first week has two days in 1999: Friday, January 1 and Saturday, January 2. The last week has six days in 1999, and ends on Friday, December 31. If there were only 364 days in a year, and if the year started on a Sunday, then every year would have exactly 52 weeks. However, we aren't that lucky, and no year ever has fewer than 53 weeks. As fate would have it, the year 2000 has 54 weeks! The first week has one day: Saturday, January 1, and the 54th week has one day: Sunday, December 31. (see footnote #2 for why we called this a Y2K problem). It turns out that a 54-week year happens once every 28 years, so the last time was 1972 ... well before the birth of many software packages now in common use." Source and further information: http://www.allegro.com/papers/54.html

52 weeks in a year

52.2 if my memory serves me well!

not enough

52... FAIL!!